Eat real food.
Not packaged food or ready meals or fast food joint food or stuff in a packet with all sorts of supposed nutritional claims.
Eat real food that you cook yourself.
It will save your life.
I've spent my life drinking like a drunken fish and sleeping with whoever will have me. But through it all I have eaten well.
And now, in my middle years, despite my depraved life, I am a healthy man.
So, whatever you do, eat well.