Then you fill out the form to see if you can avoid the penalty. I'm guessing you don't make enough to qualify for subsidies/tax credits and your state didn't expand medicaid.
https://www.healthcare.gov/exemptions/
Read all the exemptions, and if one applies, scroll down and select the right form. I can't think of anyone who really can't afford it and hasn't had at least one of those situations. I know you likely qualify because of this:
So you apply for that and pay no extra taxes and no insurance premiums. You still don't get coverage, but you don't have to pay anything, either.