My ex-wife worked for non profit for most of our marriage, these are my summations of her frustrations over the years. She and I both were pretty severely depressed during this period as well, so keep that in mind:
they are run like a business, and can be just as political
you will be overworked and under paid
career prospects are limited
the board is sometimes full of sexist idiots
you will meet some wonderful people but still sometimes work with and for idiots
All that being said you are doing something that typically is doing good for humanity.
My lease has two things. Mow the lawn AND abide by any HOA shit, so I had to mow the lawn to their standards and do the random bullshit they came up with. My garbage cans were in front of my house for 9 months and then all of a sudden it was a problem. Fuck HOA’s and land bastards