Lena Dunham: 'Exercise has helped with my anxiety in ways I never dreamed possible.'

If you follow her on Instagram, you’ve probably noticed Lena Dunham has really been getting into exercise lately.

Over the past few months, the actress and author has been practising AcroYoga, documenting her impressive progress with her signature amusing commentary.

RELATED: The secret to Kate Hudson’s fitness is in her handbag.

While her Girls character Hannah Horvath resists exercise — remember the scene where Adam takes her running? — Dunham is clearly loving it. Yet her primary motivation for keeping fit isn’t necessarily what you’d expect of a Hollywood actress. (Post continues after gallery.)

Over the weekend, the 28-year-old posted a photo of herself at the studio of celebrity trainer Tracey Anderson, taking the opportunity to explain why her exercise regimen has become so important to her. Turns out, it has little to do with aesthetics; keeping physically fit has helped Dunham manage her mental health.

“Promised myself I would not let exercise be the first thing to go by the wayside when I got busy with Girls Season 5 and here is why: it has helped with my anxiety in ways I never dreamed possible,” she writes.

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“To those struggling with anxiety, OCD, depression: I know it’s mad annoying when people tell you to exercise, and it took me about 16 medicated years to listen. I’m glad I did. It ain’t about the ass, it’s about the brain. Thank you @tracyandersonmethod for showing me the light… #notsponsored #stillmedicated.”

It’s an important message for anyone living with a mental illness to hear. So often we focus on the purely physical benefits of exercising, like muscle tone, weight loss and preventing disease. Yet clinical research has also established the benefits of exercise in alleviating many of the symptoms of anxiety and depression, and potentially curbing their onset.

“Everyone thinks about [exercise] as the means to a better body, a ‘bikini body’, looking great in jeans, being skinny. It’s all based around weight, whereas in my brain I see exercise as something that’s all about your head," fitness guru Michelle Bridges told The Glow earlier this year.

"There’s so much research on depression and how good exercise is for you. I think people forget about that."

According to the Black Dog Institute, research suggests just 30 minutes of vigorous movement every day may improve sleep patterns, increase energy and create a distraction from worrying or negative thoughts. This is because it's believed to increase the brain's serotonin levels, which aid in regulating functions like mood and sleep.

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Although exercise isn't considered a standalone treatment for mood disorders, the Royal Australian and New Zealand College of Psychiatrists recommends it be used to complement other treatments, as it can "help recovery, prevent recurrences, and manage the side effects of some medications," ABC Health and Wellbeing reports.

Even if you're not living with a mental illness, exercise can do great things for your wellbeing and your mood. For instance, psychologists consider it an crucial part of stress management.

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"Exercise is a non-negotiable for stress management. You can’t not do it ; it’s what dissipates the adrenalin out of you. It helps you think more clearly and make better decisions," says clinical psychologist Dr Suzy Green.

If you've ever seen Legally Blonde, you'll also be familiar with the notion that "exercises gives you endorphins," which can boost your mood. All the more reason to pull on your runners, or make like Lena Dunham and try a new exercise class. Even if you don't see physical results straight away, you'll probably feel those good vibes within minutes of moving.

How do you find exercise affects your mood and wellbeing?