I'm not sure people fully understand: this shutdown will last for months.
The ones in 1995/1996 added up to 28 days. This one will last far longer.
Start contacting your Congressman now telling them that you do not support this. If it's a Republican tell them you'll not only not vote for them in the general election - you'll participate in the Republican primary and support any moderate challenger. And maybe that's a lie if you can't participate, but lie away.
If you have a Democratic Congressman, tell them to stand firm. Tell them that a lot because the pressure will grow over the next several months.