Warning: My tight grip on the router gave me hand cramps for days
I was working on a detailed edge profile and held the router way too tight for hours. By the end of the day, my hand was locked up and sore. A more experienced cabinetmaker saw me and said to relax my grip and let the tool do the work. Now I make sure to take short breaks every twenty minutes to shake out my hands. It feels silly, but it keeps the cramps away and my cuts stay smooth. That small change saved me from a lot of pain.
Actually, keeping a firm grip is sometimes necessary for control and safety. A totally relaxed hand can make the tool wobble on tricky cuts. You just need to find a balance so you're not white-knuckling it the whole time.