Exercise releases a lot of different substances in your body and brain, including endorphins, neurotransmitters, endocannabinoids, and neurotrophic factors. Many of those are the same ones that are targeted by antidepressant and anxiety medications.

Scientists have started calling some of these substances “hope molecules” because of how they can boost optimism and mental well-being. They activate receptors that create feelings of happiness and joy, generating the “feel-good” effects of exercise.

Exercise doesn’t just light up the receptors that help you feel good, over time it also creates more of those receptors. Your brain becomes more sensitive to the effects of those hope molecules and you’re more likely to feel them even more strongly if you stick with your exercise program.

Those substances can also help re-wire your brain. Neurotrophic factors, which are proteins that help protect and grow brain cells, are reliably released through exercise. One of those in particular, which is called brain derived neurotrophic factor (BDNF), has been called “miracle-gro for the brain”, and goes to work creating connections between brain cells, protecting existing brain cells, and even helping build new ones in some parts of your brain.

Exercise can also help regulate a system in your brain called the Hypothalamic-Pituitary-Adrenal (HPA) axis. That system responds to stress, releasing the stress hormone cortisol and promoting inflammation. The HPA axis tends to be overactive in people with anxiety. Exercise helps control that system, releasing a hormone called atrial natriuretic peptide which calms it down.

Your body is constantly sending you signals. The skill of listening to and understanding those signals is called interoception.

Some of those signals are pretty obvious. Your body lets you know when you need energy from food by making you feel hungry. When you’re starting to get dehydrated and need to replenish fluids, you feel thirsty. When you need to sleep to reinvigorate your mind and repair the cellular damage that accumulates during the day, you feel tired. But even those clear signals are easy to overlook or push away.

You feel tired but you want to watch your favorite show, so you keep the tv on and stay up anyway. You’re hungry but you have a work deadline, so you skip lunch. If you keep ignoring them, over time you stop noticing these signals.

Your body also lets you know when you’re starting to get anxious or depressed. You might feel a change in your breathing or your heart rate. You might feel muscle tension, fatigue, or queasiness in your stomach. If you’ve lost touch with your body, you often won’t feel those sensations until it’s too late.

Strength training can help you start listening again. It forces you to pay attention to how you move and what’s going on in your body. With practice you learn to feel and activate the right muscles in each exercise, and you get better at noticing subtle changes in your heart rate and breathing.

Getting back in tune with your body allows you to intervene when you start to feel anxious or depressed, before it becomes a problem. You can practice some deep breathing or reframe the situation. This puts you back in control of your thoughts and feelings.

Strength training can help you build the kind of unshakeable confidence that has nothing to do with the way your body looks. It does that by providing “mastery experiences”, which are opportunities to achieve small goals or build skills.

Strength training teaches you how to be patient, persistent, and resilient in the face of obstacles. It gives you practice at challenging yourself and overcoming those challenges. It reinforces a positive self-identity of someone who follows through on their plans, is capable of change, and believes in themselves.

When you train, you get a chance to show yourself (and others) that you are strong and capable. And you get to go a step further, creating feelings and emotions rather than just knowledge.

When you lift a heavy weight, you don’t just know that you’re strong, you get to really feel it. When you push yourself a little harder even though your muscles are burning, you feel capable of doing hard things without giving up. If you can complete one more rep than last time or lift a slightly heavier weight, you feel yourself improving.

It’s common for people with depression or anxiety to avoid discomfort. That’s totally understandable. It’s hard enough to face difficult situations and get out of your comfort zone, and it’s even harder when you have anxiety and depression weighing you down.

But when you avoid hard things, your world shrinks. You miss out on opportunities and experiences. If you want to thrive and achieve your full potential, you have to be willing to deal with discomfort.

This is one of the biggest mental health benefits of strength training. It gives you opportunities to practice the skill of pushing through discomfort in a safe and controlled environment.

Out in the world, it’s scary when your heart starts pounding or you feel suddenly fatigued. You don’t always know why those things are happening and if you’re going to be ok. You don’t know whether you’ll be able to handle a new or difficult situation. There’s uncertainty, and that’s a difficult thing to deal with.

In the gym, though, you know exactly why your heart rate is up and your muscles are burning. You’re in control of the weights, and you can stop and rest whenever you want.

Over time, you get used to feeling uncomfortable. It doesn’t feel frightening and out of control anymore. You learn that you’re strong and resilient enough to face discomfort and come out better on the other side. You can choose to lean into discomfort and use it to grow and improve.

When you feel the urge to turn away from discomfort in your daily life, like the instinct to skip a social event where you might not know anyone or turn down a work project because you’re not confident you can complete it, you can remember that in your last workout you picked up a heavy weight and carried it all the way across the gym floor. You pushed yourself even though you were tired. You felt out of breath, and you kept going. You’re strong and you can do hard things.

We all have ideas about who we are and what we’re capable of. With depression and anxiety, those ideas sometimes hold us back.

Maybe you think of yourself as a person who never follows through and isn’t capable of achieving big things. You might see yourself as someone who shrinks away from hard situations, or who gets easily discouraged or overwhelmed. You might have a habit of taking things personally, ruminating on the past, or worrying about the future, and you might feel unable to change those habits.

Often these ideas and thought patterns are deeply ingrained. Those narratives feel true, but guess what… they’re not. Your thoughts and feelings are just thoughts and feelings, they are not reality. They’re just how you perceive reality.

You can try to talk yourself out of those feelings all you want, but in my experience, that doesn’t work very well. You can’t always use your mind to change your mind. But you can use your body to change your mind.

It’s taking action and creating positive experiences that can change your self-concept.

This is where strength training comes in. In the gym, you can prove to yourself, through your actions, that you are becoming the kind of person you want to be. Every repetition, every small improvement, is an opportunity to challenge your unhelpful thinking patterns.

The neurochemical release you get during and after a workout can help facilitate the process of neuroplasticity, carving out new neural pathways that include healthier thinking patterns.

You can practice being resilient, capable, and strong during your workouts, in small but consistent ways, and over time you’ll start to see yourself as a different person and truly feel and believe in that new identity. It really can change your life!

Very few fitness professionals are creating workouts with mental health in mind. I’m one of those few.

Here’s a sample of the science-backed methods I use with my clients (and myself) to harness the power of strength training for improving mental well-being while building physical strength and overall health.

I’ve written blog posts about each of these methods, click the titles to learn more.

• Intention-Setting for reinforcing the connection between what clients achieve in the gym and their new self-identity and thinking patterns

• Ramp Down Sets for optimizing the mood boost and fatigue-fighting effects post-workout

• Time Under Tension and Drop Sets for getting comfortable with discomfort

• Parasympathetic Breathing for activating the relaxation response after exercise