Shout out to the 40s massive 
(This echoes many of the themes already posted above, but I found it quite cathartic to write)
TL;DR as you get older you decline physically but often become more content. You tend to know what you like and give less of a fuck. Make sure you keep your friends and have hobbies though.
Details
Until I hit my late 30s I felt I was on a conveyor belt through life. Striving to meet the expectations of others coupled with fear of somehow having failed to achieve the arbitrary goals I had set for myself.
When I hit 40 it all unravelled a bit (see the midlife crisis thread), but I popped out the other side and have really enjoyed my 40s. Probably my best decade so far. Coming through a crisis forced me to re-evaluate my life and I realised many of my assumptions were false. It was both unsettling and liberating at the same time.
I still have most of the same hangups, but their intensity has faded and I can look at them in a slightly detached way. My inner voice is more able to tell me that a particular negative thought is not real, itās just one of the thought patterns that I have developed over the years and I can safely ignore it. Rather than trying to think my way out of things, which always used to end up tying me in knots and cause anxiety and sometimes depression.
I used to take work far too seriously. I think this was mainly through fear of missing out on the next opportunity if I eased off. But then I got a job with more seniority and the stress that comes with it. I absolutely hated it because it overshadowed every aspect of my life. I wondered why I had just assumed this was the natural direction to head in and (after a lot of prevarication and anxiety) decided to take a step back to focus more on interesting work where I was more in control of my own time. Iām very fortunate to be able to do this and realise itās not an option open to everyone. But god, the idea of giving so many of your waking hours to an employer (and being scared not to do that) seems absurd to me now. Itās a massive collective illusion folks.
Health-wise I havenāt really looked after myself very well and I regret that. I had a bit of a scare recently and it knocked me back and made me feel very mortal. Now the dust has settled, I feel quite positive about making some lifestyle changes, but thatās set against a lifetime of believing I could not succeed in that area. Feels like a constant struggle against my inner weaknesses.
Itās easy to drift away from your friends, especially if you have young kids, and men in particular have to be really careful about that (in our current gender-role biased society). Iāve had to make a special effort to maintain or rebuild certain friendships recently, because when I crises have occurred, I realised that my support network was not what it used to be. To be honest, part of the reason I started posting on DiS was to be more sociable in general, and ājoin inā more rather than always feeling like I was on the margins.
Aches, pains, noises when getting off the sofa, baldness, grey hairs, failing eyesight, inexorable weight gain, massive hangovers, backache when standing up at gigs, hairy ears, constant tiredness. All these are givens, but theyāre actually not that bad and can be mitigated through acceptance.
So, as my half-century looms, I am generally more content than Iāve ever been.
My relationships with my partner, my kids and my extended family are really good, and I feel better able to get through the ups and downs without it seeming like an existential threat if people arenāt 100% happy all the time.
I need excitement much less, and Iām able to enjoy simple things without feeling like Iām wasting time. Any activity that can switch off excessive thoughts and rumination is good. Video and board games, playing music, going for walks, drawing, crafts, gardening (most of the things you can do in a shed, basically) take on a deeper meaning and you can actually feel them having a calming effect when you do them. So yes, you start enjoying all that stuff you thought your parents were losers for doing.
Keeping an open mind and being open to new experiences is really important (for me anyway). Cultural things and travel satisfy my need for novelty now.
And others have mentioned this, but everything seems much more poignant now. I canāt remember crying much at all between my teens and mid-twenties, but almost everything makes me well-up now - music, Springwatch, a nice view. My kids take the piss out of me because I cried during Kung Fu Panda 3. But itās OK because I am more in touch with my emotions and donāt bottle things up.
