What can I possibly do to improve my life expectancy after heart attack and stents?

[Hermetic]

I am 58yo. Gave up smoking 15 years ago. Don't drink. Walk 3-4 miles daily. Swim. Eat very well - fruit, vegetables, brown rice, fish, white meat, no junk. I do all the right things. Regular medical check ups. Not overweight. BP and all my numbers are good. Yet 2 months ago I had a massive heart attack. I required 2 stents. I don't understand why the heart attack occurred. Blood sugar normal. No family history of heart disease. (My 'bad' cholesterol was slightly high but a series of doctors told me it didn't require medication.) Now I'm advised to make lifestyle changes. What changes? I've been doing everything they recommend for years, and it's made no difference. Now I'm on a barrage of meds, statins, aspirin, etc. but otherwise what else can I do? What is my life expectancy in these circumstances? If I've been doing everything right for years and I still have an MI, what then? What more can I do to improve my chances? What can I change? Are the meds enough? To be honest, I feel like it's a lottery.