Water Works
I do not drink enough water. I am the worst in fact, which I feel is not an exaggeration. Why I don't at least get thirsty more often than I do, I have no idea. When I happen to remember to hydrate I grab a glass with the intent to reuse it, keeping it close by for refills. In an effort to remember to down some good H20 I married my love of lists with a little recycling.
The resulting product is a static cling that can be stuck onto any smooth surface. Simply smack on, drink, and check off with a dry erase marker after a long gulp. Start all over again after 8 glasses. I created a handy vinyl carrying case to store it along with instructions (on the chance that one forgets what the end game is and how to get there). One of these contraptions can be yours if you need some obvious nudging, or just love giving yourself a pat on the back for completing something. Purchase* here for $7. Bottoms up!
*Mini marker not included, but if you ask nicely I can include one. Color likely will not be blue however. Why should that stop progress though?