Hi,
Yeah, I clench up a lot for absolutely no reason. I didn't realize I was doing this, just clenching my body without knowing, until a couple months ago when I started pool and land therapy. They would be telling me to relax, and I would be like, I am, but then when I started paying attention, I really was all clenched up. I now watch out for it in my daily life, and when I realize I am what the therapists call "holding," I breathe deeply and focus on relaxing that part of me. Deep breathing is something else I have to practice, as I have a habit of shallow breathing, too.