Write "field reports." Make it a daily thing. You don't need to post them anywhere, but just write down what you did well and what you did badly during the day, every day, until it becomes a habit. Every once in a while, come up with a new routine or something and learn it. Always be improving yourself, and expanding your horizons; the field reports will help you see your progress.
The key to keeping yourself motivated is to keep yourself interested in what you are doing, and the way to keep yourself interested is to always be trying to gain a deeper understanding and appreciation of your subject matter.
It is frustrating at first, just like any new activity when you are still learning the ropes, but once you begin to see your own progress, you will have no trouble staying motivated, because you will continually want to get better at what you are doing.