You've no doubt developed a few insights over years, so share them with someone who's willing to listen. Research cited by the Big Brothers Big Sisters organization shows that a young person who is matched with a mentor for one year or longer is more likely to graduate high school, attend college and to show more respect to adults. Reach out to Big Brothers Big Sisters or check to see if your employer or alma mater has a mentoring program.
Calories burned: 200 for an hour of standing or playing with kids. To make your meet-ups more varied, consider combining activities: make kites and then fly them outside; walk to the ballpark instead of driving; prepare a healthy feast using fresh veggies and fruit.
Muscles worked: Sky's the limit.
Karmic bonus: Your mentee gets a fresh, unbiased take and encouragement on her academic interests and career aspirations.
Next: The busy person's guide to volunteering