Once in a while I go back to reading things I have written months or even years before and surprise myself. Sometimes it's the level of eloquence in which I presented the ideas, other times just the idea it self. I find that coming to these realisations is a good way to re-energise my self-confidence and motivation. It reminds me of how good I can be and how high I have raised the bar for myself.
Thus creating a habit of reading or reviewing old works might be a good idea to keep me moving forward.