If having a routine calms you, your writing routine can be a balm on your frazzled nerves.
Regardless of how uncontrollable and chaotic your real life has been, your well plotted story remains exactly the way you left it. The characters, if you’ve gotten the plotline right, will do what you want them to do*. But regardless of the quality of the writing, just following the routine of writing out a few hundred words, or of putting together an outline can be very calming.
Even when your writing is making you anxious, it’s still less stressful than the rest of life AND it gives you something worthy worrying over. Seriously. Your roof might have a leak, your coworkers might be terrible human beings, your family might be making you feel like just driving away, but the stress of writing is not only predictable and comforting, but you can actually do something about it with minimal effort. Bliss!
*If the character and plot don’t mesh right, all bets are off.