I just pushed my self to walk and I got pretty pretty fast. Amazing, concidering when I was in Montreal I couldn't walk much, or even sit (lots of pain). I was uber tired, etc.
Now I'm doing really good. The first month was probably the hardest and I had to take it easy, but try to walk around as much as I could. I went for a walk almost every day. It also helped that I had a friend from the UK down and we'd go to the mall, walk around, and do all sorts of things. I don't have a car, so walking is what I do. It got better every week.
I'm now to the point of running and dancing.

Others took much longer. I known people to take 2-3 months before they had much energy, some even longer. It really varies person to person. I got a lot of jelousy thrown at me because a week after I got back from Montreal I went out to gothy night and danced a song and a half... not even a month post-op. I was very tired after that song and a half. Now I can dance most of the night. I keep getting other post-ops saying, "How are you moving like that? How are you walking around all the time? How come you're healed so fast?"
I swear, walking helps you heal quickly. You can just do some every day, and do more each day. Just take it easy, but make a goal. 5-10 for a week every day, 20-30 the next week, etc, etc.
The most I've walked so far was 40 blocks on Monday, because I missed the night bus and walked home. I think it just took over an hour and included a hill.
I also walked a lot before surgery, so I think that played into things somehow.