I was the Poster Boy for post-op complications. I probably hit every speed bump on the road to recovery (search my posts from Feb. 2011 onward to read it all). In spite of all that, though, I was back at work (office job, high stress) at 6 weeks. I started out at 4 hours/day, then 6, then 8, then back to my usual 10-hour days by about 3 months.
I was not deemed "healed enough" for cardiac rehab until I was 12 weeks out. During weeks 5-12, though, I began gentle walking, and was soon up to walking a couple of miles a day. I remember that on my first walk, I left the house to walk to the mailbox about 2 blocks away. Once I got there, I remember thinking, "Holy Cr*%! I'm so tired I may not make it back!" That feeling didn't last more than a couple of days. I gradually increased the length of my walks without issue.
Once I started rehab, I began to feel much more normal. I became the class clown. When the rehab tech would ask "Do you think you can do XYZ?" I would answer "Bring it on!" I tried (and generally succeeded) to do everything at 110% through rehab. In fact, I had rehab on Monday, Wednesday and Friday afternoons. On Tuesday and Thursday I did the same routines at my regular fitness center. Oh, and during rehab I was already working full-time as well (at age 63).
I can't really say at what time point I really felt "normal" but for most activities I was back at normal levels before 6 months. The one exception I can still remember is that I didn't feel comfortable doing push-ups until about a year. I was capable of doing them, it just didn't feel right. I think it was related to how my chest muscles healed, and the relatively lighter workouts I had done since surgery.
I could go on and on, but I'm at work now and need to get back into the job. (At age 71, no less.) If you want to discuss my own specific experiences "one-to-one" then just sign up to create a user name here and PM me. I will answer any questions I can for you.