Are you more motivated by winning or by not losing?

Think about the why. Whatever you do, whether it's a big project or a small task, has a reason for being. Sometimes it is not very obvious, but if you stop to think for a moment, you should find a higher-level motivation for doing something you don't feel like doing right now (if you ultimately cannot find a compelling reason to do something, it is quite possible that you simply shouldn't be doing it).

Think about what you lose. This is the opposite approach to the previous one. Instead of thinking about what you can gain, think about what you might lose if you don't complete that work. There are studies that show that loss aversion is more motivating (practically double) than the possibility of making gains. In general, we will put more effort into not losing €50 than into earning €50.

Try to make it fun. Sometimes, a routine and boring task can become something interesting if you are able to do it in a different way. I hate doing administrative tasks, but if I put on my iPod with a good selection of rock music, the time flies by. Give free rein to your creativity.