For me it is; heck yeah. Not from external stressors - I mean, I've never been absolutely poor, or had a life-threatening disease (well, technically, once, but I felt fine and it was resolved quickly, so it doesn't count!), or been the victim of a violent crime or abusive relationship, or dealt with infertility or even the loss of a family member. My life is ridiculously easy by all sane standards. And yet, I have a supreme talent for making things hard for myself. I overthink, I stress, I'm prone to depression and a bit Aspie, and yes, little things are hard. Always have been.
To take a very trivial example, I used to HATE getting haircuts as a kid, because I was convinced everyone would look at me and make comments. For some reason, being looked at by an acquaintance and hearing the innocuous comment "Oh, you got your hair cut!" filled me with deep shame and humiliation and embarrassment. So whenever Mum started threatening to cut my tangly hair, I would walk around for weeks with dread and horror in my heart, and act out; she'd have to drag me literally kicking and screaming to the hairdresser; and for weeks afterwards I'd cringe and scowl whenever I saw someone I knew approaching. Petty? Yes, but it blighted my young life... until I turned 13 and decided to never have short hair again. And I still don't. :p
So that solved the hair problem. But I think I still find things more difficult than "normal" people. I admire people who can casually make life-changing, grownup decisions like "Hey, babies are cool, let's have one!" or "Let's move to England for a year, it'll be fun!" or even "We have some money saved up, let's fly to the islands for a week". I can't do that. I overthink everything. You should have seen how much research I did for a holiday we were going to take later this year - heck, we planned a baby round it! (Now we have the baby, but are too broke for the trip. Heh. Oh well, it's a nice baby.)
I dread to think how my none-too-robust mental health will deal with ageing, menopause and any actual crises that come up in life. It won't be pretty. I really don't know how people do it.