I have to exercise or I feel like shit. I think that people that don't exercise have accepted feeling like shit as the "default" and somehow don't mind it.
For me, the difference in my mental and physical health, to say nothing of my alertness and mental clarity, is night and day when I'm running every day. I run 3 miles a day (been running since I was 12 years old, sometimes competitively -- at my best, I was one of the top high school runners in the state of Pennsylvania); it takes only 20 minutes a day, relieves stress, and I feel very relaxed and lucid afterwards. I also noticed that the same amount of sleep takes me farther when I'm exercising than when I'm not. The resultant energy boost tops caffeine.
When I find that I can't run (because of weather, scheduling issues, traveling, etc.), I just do some simple yoga stretches for 15 minutes, and even that really helps my attitude and alertness.
EDIT: Growing up, I was always the scrawny nerdy computer hacker kid that got picked last in gym class who couldn't even catch a ball who was so fed up with it all that I trained and worked my way up from last place runner to state-caliber athlete, so if I can do it, you can, too. I still can't catch a football though.
For me, the difference in my mental and physical health, to say nothing of my alertness and mental clarity, is night and day when I'm running every day. I run 3 miles a day (been running since I was 12 years old, sometimes competitively -- at my best, I was one of the top high school runners in the state of Pennsylvania); it takes only 20 minutes a day, relieves stress, and I feel very relaxed and lucid afterwards. I also noticed that the same amount of sleep takes me farther when I'm exercising than when I'm not. The resultant energy boost tops caffeine.
When I find that I can't run (because of weather, scheduling issues, traveling, etc.), I just do some simple yoga stretches for 15 minutes, and even that really helps my attitude and alertness.
EDIT: Growing up, I was always the scrawny nerdy computer hacker kid that got picked last in gym class who couldn't even catch a ball who was so fed up with it all that I trained and worked my way up from last place runner to state-caliber athlete, so if I can do it, you can, too. I still can't catch a football though.