Hello,
I admire your positive outlook towards your health and i really appreciate it.
Coming to your question, after placing
stent in coronary arteries, a person can resume his normal activities after a day or two, one can do walking for 20 minutes a day after a week and one can join a gym and do all the exercises after 4 to 6 months of placing a stent. But you need to remember few things like take your medications regularly, do not over burden your body by doing heavy exercises, eat healthy and controlled diet, avoid
smoking and alcohol, regular follow up with your cardiologist etc.
So yes, you can do sit ups, running and jumping, but in moderation! You can do bowling and water skiing once in a month and its fine. Actually all these exercises are beneficial to your heart, but keep those in moderation, do not over burden your heart.
Hope this answers your question and let me know directly if you have any further follow up queries, i will be happy to guide you in right direction.