dunno if its age or running.
In my younger days I used to drink like a fish, 75-100 units a week was the norm, now I hardly touch the stuff, yet when we go out and I'm on it, I can more than 'handle my own' - recent stag do in the 'dam I was getting to bed at 6am, so maybe it's 'pacing yourself - it is a running thread after all!!!
However some days a couple of pints leaves me wobbly....
The downside to age is that when I was 25, I could get completely wank&&ed and get to bed at 4am, up at 6 and do a full days work, now if I'm any later than 1am, I feel wasted the next day and steer clear for a week........