Is ashtanga yoga, walking, and good nutrition enough to keep one in shape?

[chrisandniki]

I currently do about an hour of the primary series of Ashtanga yoga in the morning, followed by a good 30 minute walk with our dog. Is that, along with following a sensible diet enough exercise for me?

I'm a 30-something male who works an office job. I do have access to a gym at lunch, but I have to admit -- I enjoy the yoga much more than a gym.

Let me know your thoughts.