Riding is something you have for life. Sure you may forgot what diagonal or what lead to get on, but after a reminder from a friend or trainer it will come back to you! Getting a piece of paper and imagine riding will help, maybe a dressage test to help remember. Enter at a walk, heels down, deep seat, then trot, with the correct diagonal, heels down, no pulling reins, etc. Good luck and best wishes!
“Good things come to those who wait… greater things come to those who get off their ass and do anything to make it happen.” - Unknown