We took a day trip by car to the Mayan pyramids of Coba, the only pyramids in the area that you can still climb ~ at Chichen Itza you can climb portions of some structures, and at Tulum they are all roped off as in a sculpture garden. Photos from Coba: view from the top of the pyramid we climbed and bicycle rentals.
Years ago, I would have wilted, out of breath, legs rubbery en route to the top. But my legs were strong. I was not winded. Almost two years of regular workouts have made a tremendous difference. My husband and the 9 year old practically bounced down the stairs ahead of us, fearless. The 6 year old descended slowly with me, step by step. My acrophobia [not fear of acrobats... fear of heights] did not stop me.