Yes. You should avoid saunas and strenuous exercise for at least two to three weeks after having a tattoo to avoid causing the ink to fade too quickly. To reiterate, perspiration is considered moisture and may be detrimental to a tattoo's healing process. While some perspiration is to be expected (after all, you are human), you should try to avoid doing things that will leave you feeling like you need to immediately plunge into a body of water.