The first solution is to become a lot more conscious of when you use your leg and the response you expect. I tell riders that they should focus on NOT using the leg. A specific mental effort to keep it still, and a specific conscious choice to break the stillness by applying the leg when needed. When the horse ignores the leg there must enough motivation delivered to the horse for ignoring it, different horses have different levels of motivation. Then as a rider you must be responsible enough to be quiet again and allow the horse to move forwards. Nothing worse than the horse going forwards and his reward being a rider bumping on its back being left behind.

Mary often asks her pupils a trick question which goes "Who's responsibility is it to keep the horse going?". Inevitably pupils answer "Its my responsibility". In truth it is the responsibility of the horse to keep doing what you last told it to do, and it is your responsibility to make the horse's job as easy as possible. A horse should be going forwards as a default and not need nagging every stride.