If you treat your body badly when you're young does it ruin you in later life?

[InconstantMoon]

I'm just thinking of all the (mainly) passive smoking I endured in the 80s (worked in pubs) and also a steady diet of alcohol in my twenties and thirties. I take care of myself now but I guess as I'm getting older I'm scaring myself that this might somehow get me!

Dundee uni published a survey on the health of bar staff, before and 3 months after the smoking ban in pubs. They showed a huge improvement in lung function. Accepted wisdom is that ten years after stopping smoking, a smoker’s risk of cancer is almost back to that of nonsmokers.
The one thing that is not reversible is copd. But you would need long term significant exposure, to result in that.
Alcohol increases the risk of several cancers, but again, you would be unlucky if a short period of youthful excess put you in that group.
In any case, you cannot rewrite your history!
You are now doing all the right things for your health, so simply continue on that path to maximise your chance of a long healthy life. There is no point worrying about things you can’t change.

That's very sensible, thank you