Once you lose momentum, it can be pretty hard to get back. But it is still possible. When Michael Jordan returned after his first retirement, it was obvious that his elite Bulls team had lost some momentum along with some swagger. They did not win the championship that year but it was still a great season for them. They built some momentum and worked off of that. The season after they broke records, made history, and won the championship.
If you have any setbacks, try to learn from it, evaluate the situation and consistently improve. Once you hit a hot streak then ride that X factor until the wheels fall off.
Bill Zanker, founder of The Learning Annex, had a keen sense of his business' momentum. Once he finally booked Donald Trump to speak to his students he knew he had the momentum he needed to skyrocket his business to the sky and beyond. He continued to book Donald Trump on numerous occasions along with other well known celebrities. The Learning Annex took off.
Whatever it is you are doing for a profession, you must build your momentum. And once you are in the zone...stay in there for as long as possible!