You could learn to ride a bike in a few days. Not that that's necessarily the answer in a big, rural state like Maine, with snow on the way, but finding a bike and learning to ride is a fairly quick, easy thing to do. Dealing with getting arrested for driving without a license will affect you for years.

Being thin isn't the same thing as being healthy. Quite the opposite, if you're underweight. Eating decent food and exercising will put on muscle. You'll improve balance and coordination, and the secondary effects of improved cardio and respiratory health can be life-changing in themselves. Your body will feel better, and that'll affect your mind, too!

I've tried dozens of approaches to dealing with depression and anxiety. None of them helped much... except exercise. Turns out I like felling trees. It's hard work, and it's potentially dangerous, which keeps me on my toes. After many passes at working out at a gym, playing sports, walking more & doing a twice-daily pushup-situp-etc routine... felling trees taught me that physical exercise is a magical method of working hard that I actually found really fun! Learning that was profound, in terms of showing me what was possible. After a life of depression, I could start changing course. Before that, I didn't really believe I could do anything to change my constant depression.