For many, celebrating a birthday is synonymous with cake [1] and ice cream. Don't tell that to Naomi Watts [2] — the actress celebrated her 41st birthday on Monday by biking around New York City with her beau, Liev Schreiber [3]. I think it's OK to celebrate a little when the occasion arises, but I have also been known to start my birthday off with a bike ride with my man.

What about you? Do you let you indulge on your big day, or do you incorporate fun fitness activities like Naomi?