Although you can download all the productivity apps in the world (and I have), no app will make you care about what you have to do like the Rule of 3. The rule is dead simple:
1. At the beginning of every day, mentally fast-forward to the end of the day, and ask yourself: When the day is over, what three things will I want to have accomplished? Write those three things down.
2. Do the same at the beginning of every week.
The three things you identify then become your focus for the day and the week ahead.