Anatomy I & II in college made me start running. After I learned running helps circulate the lymphatic system, I've been running ever since. Also, I've noticed running really helps to take your mind off things, especially stresses of the day!
Good for you that you're actually training for something. We really don't have any kind of marathons or anything like that around here.
I try to run at least 8 miles every week. Sometimes I can't, but when I do, I feel great.
Sadly, though, I do all my running on the treadmill (my area has become too dangerous to run outside
Every week, I try to follow this schedule:
Sunday: Start at 5.0 mph for 45 minutes, but increase speed by .1 of a mile every minute, with no incline. Either that, or I'll run constantly at 6.5 mph for 45 minutes with an incline cycle level of 0-4 every 2 minutes 15 seconds.
Tuesday: Run at 7.8 mph for about 10-15 minutes on a level (0) incline
Thursday: Run at 6.0 mph for about 5-10 minutes at a cycling incline interval between 5-10. This one's really tough!