Give blood - and get a free snack and drink afterwards! Check out my later blog for more info.
Sign up to become an organ and tissue donor. Don't assume you are too young, too old, or that your chronic medical conditions would necessarily be an issue. Check out this link for more info. I've just watched Dr Chris Barry, a transplant surgeon, give an passionate short talk on TEDx Talk too.
Know how to give CPR. Check out this funny but informative video.
Can you use an Epipen? Refresh your memory and teach family and friends, as well as set reminders to make sure your Epipen doesn't expire when you really need it. Check out the Epiclub website.