I don't believe it can be generalised or categorised by age. Circumstances vary so much. My mum used to quote a German saying which translates as "little children, little worries, big children, big worries" so what seems insurmountable in your teens (acne, exams, friends, body image) may be replaced in your 20's and 30's (getting a mortgage,and house, promotion at work, babies) in your 40's (children's schools, house prices, maybe promotion or lack of it) and in your 60's and over (pension, health issues, distant grown up children, housing -again- loneliness) .
What makes you HAPPY will change too. I suppose it all depends on the balance, but by our later years we have perhaps learned to take what happiness we can, while we can!