I am sorry to hear about you and your father and I hope he continues to make a full recovery and I hope you keep that BP under control!
My dad suffered a heart attack... It must have been in 2003 because it was right before my high school graduation. He was only in his late 40s (Bout 46-47 or so when it happened) and had to have a triple bypass because of it. It was pretty scary for me because heart problems and blood pressure already run on my moms side of the family. My grandfather just died a few years back from congestive heart failure.
My dad is a fairly active guy, used to play tennis and golf and work out on a weekly basis. After his heart attack it doesn't do anything too active anymore besides play golf. He lives out in Cali so I really don't know the exact details of everything he does and how he handles it (such as the exercising). In my opinion to give him encouragement let him do everything he used to do, just make sure he doesn't over-exert himself. If ever he feels tired tell him to STOP and rest. My best friend's mother was born with a hole in her heart but she still runs on the treadmill for 20-30 min, everyday. But she knows if she feels fatigued or faint to stop and just sit down.
Good luck and God bless.