Exercise: absolutely. I wish someone had told me when I was younger how dramatic an effect it has. (I mean mentally and emotionally, not physically, though obviously there are physical benefits too.) It still amazes me.
spending an hour by myself once a week
Man, I'd go insane if I only got an hour's worth of solitude a week.
Interesting. I feel like I'm the only person who hasn't noticed much of a difference, emotionally speaking, even after dramatically increasing the amount I exercise. (I biked about 8 hours a day this summer, and now that I've started work, I ride my bike to work.)
I can second this. Over the past few years I've regularly attempted to start exercising. It makes me tired, it bores me, and I just don't feel better. I know it's supposed to make you feel fit but that just isn't the case for me. I thoroughly hate it.
spending an hour by myself once a week
Man, I'd go insane if I only got an hour's worth of solitude a week.