While you take a walk try to kick stones or bricks with your toes. Afte3r a long time the muscles in your toes will become elastic and tough. You must now attempt to kick bigger stones or bricks with more fore. When you kick the objects far away practice kicking at a target. Practicing this technique will result in very good gripping stances.
NB: I'll not be held responsible for any injuries or suffering if anyone tries this techniques. It requires special guidance froma qualified instructor. I doubt you will find many instructors that know this technique as they are very old techniques and are only usually taught to special students with high potential, dedicated, respect teacher and self-respect, and patience.