I've never smoked but there are other historic factors which impact my present day ability on the bike - mostly a sedentary lifestyle where I carried around way too much weight for way too long.

I think I'll always be dragging around some degree of a 'boat anchor', which is the residual effect of not looking after myself for so many years, much like you who'll probably always have some issue with lung capacity/function as a direct result of your many years of smoking.

The way I approach it is to set my own reference points along the way and to always compare my latest performance back to where I started from - with the emphasis on I, and not someone else. So even though my ultimate performance will always be some rungs down the ladder when compared with other people of a similar age to me, I can still take a lot of comfort and positive reinforcement from seeing my own results exceed my early expectations.

If I were hugely competitive then I could become frustrated at not being able to keep up with the best in my age group, but I'm not, so I'm happy to just keep building up new personal bests.

Pat yourself on the back for quitting smoking.