Happy Birthday, Mark. The good news is there are advantages to hitting 40.
You can legitimately, shout at the kids to be quiet, while you take a nap.
Forget just about anything. Even if you don't forget something, you can use that as an excuse for all sort of "Get out of Jail" tactics.
Buy the stuff that when you were 30, you couldn't get away with.
Comfy slippers, baggy clothes, trousers that have elastic in the waist band and cardigans.
Treat yourself to a mid life crisis! Get yourself a motor bike, start going to gigs, let the wind fashion your hairstyle instead of the barber.
Start to pre book your doctor appointments. Plan to be sick on certain days (usually a Friday or Monday) and have a genuine excuse for doing so. At 40, you start falling to bits, so why not take advantage of the situation?
Forget having to give up your seat on public transport for the young mum or old gent. You need that cushion just as much as they do!
So life ain't so bad at 40.
Wait till you hit 50, that's when you can start playing with peoples minds. So much more fun. ;o)