Brian Tracy's book, Eat That Frog!: 21 Great Ways to Stop Procrastinating and Get More Done in Less Time offers advice on improving productivity and by doing what most needs to be done first. The phrase eat that frog is attributed to Mark Twain who said, "Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day." Brian Tracy advises, eat the biggest, ugliest most important frog first then focus attention on other lower priority items.
The sense of accomplishment can be addictive. When we finish a difficult task our brains release reward chemicals and produce a good feeling. Repeatedly tackling and completing these tasks can lead to positive reinforcement for these behaviors and it can become a positive addictive habit.
Some of the suggestions in his book are similar to those in his book No Excuses. This text focuses on specific strategies to tackle procrastination like using the Swiss cheese method or the small bite method.
I found his ABCDE method for prioritization to be helpful. E in this list stands for eliminate. I have used his early morning method to improve productivity. The cats often wake me up early in the morning and when I am unable to go back to sleep I use the time to complete tasks requiring focused concentration and minimal distraction.
The ABCDE method of prioritizing - 5 minutes