I used to put my clients above myself, working 20+ hours a day. No more. Many clients can be abusive, squeezing as much out of you for their personal gain. They make you do all the work and they keep all the profits, like the Corporate America version of British colonialism.
... except it's at-will. If you can't negotiate a rate that makes you feel like you're not being exploited, and introduce boundaries that keep you sane, you're doing it wrong.
I'll add medicating. If you do a lot of medicating to get through your work, it's time for an exit strategy.
11. They run out of money and start paying partial invoices.