Leap years happen when we add one extra day to the end of February so that we can align our calendar with the Earth’s orbit.

For those born (estimates suggest that there are about 5 million of these people in the world, known as “leaplings”), married or who otherwise denote a significant event on that day, Feb. 29, is a special opportunity for a quadrennial celebration.

But what about the rest of us? What can the masses do to celebrate the extra 24 hours we’re gifted with today? Here we offer 29 suggestions (with a little help from gooddeedsday.org):

1. Start a new family tradition. After all, you only get a chance to do this once every four years.

2. Let someone go ahead of you in line.

3. Call your parents or grandparents unexpectedly — just to chat.

4. Compliment a co-worker at work.

5. Set up an appointment to donate blood.

6. Buy some Girl Scout cookies.

7. Offer your chair or seat to someone who needs it more than you.

8. Return your shopping cart inside to the store’s corral.

9. Give something homemade to a friend, new or old.

10. Recycle your plastic.

11. Thank a soldier, officer, first responder or veteran for their service.

12. Visit, call or bring chicken soup to someone who is ill.

13. Consider bringing coloring books and crayons to a homeless shelter.

14. Apologize for something you said or did.

15. Use a business charity box to deposit your spare change.

16. Wish someone a Happy Birthday, in person or online.

17. Visit a senior center to offer your talents, or just your time.

18. Drop off some treats at your local firehouse, police station or sheriff’s office.

19. Consider a larger-than-usual tip for your server.

20. Offer a pen to someone who needs one.

21. Contribute dog or cat food to an animal shelter.

22. Leave a book or two at a Little Library.

23. Help spruce up a communal space or garden.

24. Say hello to a neighbor.

25. Read to a child.

26. Hold the elevator door for the next person.

27. Ride a bike or take a walk.

28. Smile at a stranger.

29. Forgive someone who hurt you.