Balance - Exceptional riding isn't holding on with your legs. It's balancing on the horse, with the horse.  Use your legs for touch/feel, steadying your balance occasionally and signaling.

Everyone's given piggyback rides. But, what do you say to the kid that's breaking your ribs squeezing his legs and choking you with his death grip on your neck????? Yep. You say "Relax. I've got ya!" So does the horse for the most part. It's not like you're going to fall into his intestines. Just sit there.

Learn to relax and just sit there. Just walk around and don't steer or grip. Make sure you let your toes hang down and let loose in your thighs. If your toes are up... you're not relaxed. It's impossible to have your toes up without the muscles in your legs pulling them up. So, ergo, you're not completely relaxed.

Eventually, you can move up to trotting and cantering/loping without picking up your reins or changing the energy in your seat or gripping with your legs. You'll be so glad you can and your horse will be delighted.