What in particular? So many things...
Rarely seeing the sun (all that Oregon rain).
Hearing about the dissolution of a long-term marriage.
Watching the workload at your business slow down week by week.
Struggling to make friends in the limited free, adult time you have as a parent. (And no, befriending my kid's friends' parents hasn't been so successful)
Wanting to make a change - new job for spouse, new car, vacation somewhere sunny- and being terrified of commiting to a possible mistake.
Life isn't terrible, but it sure is harder and harder to be happy, relaxed, optimistic right now.