Keep a dated list of tasks and projects you have completed, because looking back on your achievements provides a sense of accomplishment and motivation.
There's something to be said for seeing how much you've gotten done at the end of the day. You know how satisfying it is to cross out items on your to do list, and then look back at the list to see everything you completed? A "done" list, or "anti-to-do list" as Marc Andreessen calls it, works in a similar fashion: you simply take note of each thing you get done during the day. Start out with the date and just list your "done" items underneath. Not only will this help you review your productivity at the end of each day and make you feel better about what you got done, but it can be really useful to keep around as a work log. You might want to look back in weeks or months to come to see what you were working on or how long a project took to complete.
Clever uses for plain text files that can increase your productivity - Lifehacker