This may not work for everyone but for me it works exceptionally. Most often the reason why you don't want to work on something is because you find it too hard, too boring, or too irrelevant. But if you force yourself to be bored for a while, you will eventually crave some mental stimulation.
And that's when you can pick up the task you have been avoiding and work on it with renewed interest and focus.
Of course, this requires some discipline and self-awareness. You have to resist the temptation of checking your phone, browsing the web, or doing anything else that distracts you from your boredom.
Maybe there is some psychological reason for it but I have found this technique to be very effective for overcoming procrastination and getting things done.