For me it's more that life has got far more difficult as I've got older and my my MH probes have been made worse by it. There's a pressure I feel as an adult to be a certain way and it's a blow to your self esteem if you feel you haven't achieved those things you feel you should have. I feel like a misfit in some ways I suppose, everyone around me has nice jobs, stable relationships, kids etc which were not issues when you are younger. Honestly? Relationships baffle me sometimes and I feel weird.
I also feel like I've failed at life in many ways, I thought that I would be doing a lot better at age 30. I guess it's disappointment that can lead to self esteem issues (or complete self loathing).
Being a grown up is difficult too. There's the added pressures of working, managing finances, maintaining a clean home etc and I didn't feel very prepared for it and I still struggle sometimes, it's easy to get overwhelmed.
That said, it is possible to learn to cope too, as you get older you'll have a lot more life experience which would help with your MH because you'll know how to deal with things properly and you'll perhaps be less stressed. Of course any condition that requires meds will require monitoring because meds can stop working sometimes and will need tweaking at times. That applies to all medical conditions too, whether it's diabetes, asthma etc or MH stuff.
There ate definitely things in life that have triggered MH probs for me and it does make MH issues seem a lot worse because we have added stress to cope with as well as our MH probs.
( I hope some of this makes sense and I haven't just written a load of nonsense!)