We’ve known from previous studies that volunteering in your old age keeps you from keeling over. Now a new study at the University of British Columbia has found that even for teenagers, good deeds are heart-healthy. In the experiment, just over a hundred high school students were split into two groups. One group was assigned to volunteer at an after-school program for younger children, while the other group languished on a waiting list. Ten weeks later, the kids were compared. The do-gooders scored healthier on inflammation, cholesterol levels and BMI measures. The wait-listers did less well, cardiovascularly speaking. Conclusion? Volunteering keeps you young – even if you’re only a kid.