Of course you have to rent a bike when you're in Amsterdam. I rented this one from a small shop near the place I was staying, in Jordaan.
A great day: get to the Anne Frank house early, when lines are a bit shorter, then walk a block down Bloemgracht when you've finished your tour to find the little bike shop, called Bike City. Then spend the rest of your day riding around the city. Don't miss nearby Vondelpark. There's plenty to explore, especially on bike, and it was both active and relaxing at the same time.