I love the beginning. Even when something new is challenging, it is fresh, and its unfamiliarity means that I am likely to experience a rapid improvement at first.
For me, things get harder when they get easier. When progress is less evident. The inevitable learning plateau that occurs as I accommodate new knowledge and get ready to learn more brings me down.
But to continue to succeed I need to trudge through those dull stretches and keep at it. Inevitably, with continued hard work, I can get a little better and over time maybe even notice an improvement.