The healing period won't be as bad as you fear, I promise. Looking back, I had all kinds of plans to lift weights in the early weeks and I didn't do it. Also, you really just have to strictly behave yourself for six weeks, then the biggest restrictions lift and you can gradually add more activities.
The first week or two, you will be weak and tired and your legs will not feel like they are under your power, that log leggedness everyone talks about. You won't be in pain, just fatigued and discombobulated. You'll be focusing on doing simple tasks like getting up and walking to the kitchen so won't be worried about losing fitness. But you will be walking and you will be doing those simple, first exercises, like the heal slides. This is the intense rest period.
Then you will start to feel better and get a little restless. Walking will be a treat---no pain--- and those first exercises will feel easy. Sometime in week three or four your incisions will heal and you will be able to get in the pool. This opens up new rehab/fitness opportunities. You can swim freestyle or swim with paddles or even walk/aquajog in the water. Again, your body may surprise you with what it can and can't do. (I swam 400m to start and my legs felt weird, kind of floating behind me, not helping much, so it was more of a pulling exercise. But they quickly came back on line. The first month in the pool, walking in the water, especially sideways, helped as much as anything.Getting into and out of the water was the hardest part; going up and down a ladder was a surprising challenge.)
I didn't ride a stationary bike until six weeks out, but when I could, I added that and the elliptical. And by six weeks, the walking limits begin to lift, but you are supposed to gradually add distance.So really you just have to restrain yourself for six weeks.
I found that yes, I got restless after the first few weeks, but I could satisfy myself with walking and swimming.I also found that some things I was allowed to do I couldn't do right away. The biggest was getting down on the floor. I missed getting on the floor and was dying to be free to do that at six weeks. But I was so stiff and awkward that it wasn't as much of a treat as I'd hoped. (It got better.)
Congrats on making the decision to make a change. Your neighbors will enjoy watching you crutch around the 'hood. Maybe they will bring you ice for the ice machine or casseroles to eat....