I only have one experience with heart surgery (thankfully!), but I'll agree that being at a reasonable weight and being reasonably in shape must help. I don't think it is necessary to be a world class athlete, but it does help to have reasonable muscle tone and weight. After my first couple of weeks of recovery I have had no issues of "can I really do that?" I have been able to walk increasing distances with little to no problems. Your body will tell you how far you can go, and all of my docs have said that walking is the best exercise one can do prior to rehab. The only caution on walking is if you are outdoors, remember that however far you walk, you also have to get back home! Don't go so far you have to call someone to come get you with the car. . .
I would agree that those who say that after about 4 weeks you will notice a major upswing in the pace of your recovery are correct -- at least from my experience. For the first 4 weeks or so, all I did was "exist" at home, resting, walking (some stairs, too), doing breathing exercises and taking things easy. After those 4 weeks, I once again felt ready to participate in my life, starting with a few hours at a time and building to nearly full days. I am now able to work 4-6 hours a day and will likely start rehab (Phase II) in a few weeks.
Hang in there -- it does get better.
I would agree that those who say that after about 4 weeks you will notice a major upswing in the pace of your recovery are correct -- at least from my experience. For the first 4 weeks or so, all I did was "exist" at home, resting, walking (some stairs, too), doing breathing exercises and taking things easy. After those 4 weeks, I once again felt ready to participate in my life, starting with a few hours at a time and building to nearly full days. I am now able to work 4-6 hours a day and will likely start rehab (Phase II) in a few weeks.
Hang in there -- it does get better.