First, you need "the" with heat.
"If you can't take the heat, stay out of the kitchen" is a very standard (albeit trite) experssion that means if you can't handle the criticism, don't get involved.
"I can take the heat" means I can esure the criticsm or condemntation that will come from the action. It is not appropriate to use it for other types of hardship.
If you "take a hit" it means a one-time, negative effect.
Our balance sheets will take a hit this quarter, reflecting the extra costs of renovating the New Hampshire factory.
If you admit your mistake now, your credibiltiy may take a hit in the short-term, but people will appreciate your honesty, and as long as you fix it, you won't suffer any long-term ill effects.
Please show the entire sentence/context you're trying to write about and we'll see if we can find the right expression.