Allow yourself time to teach your body what to do, extra time with your instructor may be needed to learn the mechanics. Stay in the moment-enjoy what is happening now, not fearing what could happen or what happened last time. Move toward your goals one step at a time. Don't rush, yet develop healthy challenges that are appropriate for your riding level. Give sufficient effort toward becoming a better rider. For example, if you read one word in a book every month, it will take you a very long time to finish the book. The comprehension will be very low and the book may not be very exciting. If you read a chapter or more, you will finish it in no time, comprehension will be high, and you may find that you can't put the book down!!!
Most importantly, be patient and find your perfect partner. The horse you choose needs to be right for you and only you. If you are an inexperienced horse person, a professional will be able to help you select a horse for your riding level, however when it comes to personality only you will be able to know if it is a fit. Essentially it is you and the horse that will excel together. It is this partnership that you have confidence in. You have selected this horse because of the qualities you see, the confidence he instills in you, and the trust you feel when you work together. The perfect horse will allow you to become the rider you've always wanted to be and will show you that there is nothing to fear.
Go get busy and accomplish those goals!