Ask some questions yourself: why do you study it? You can have internal reason like "I really like the subject" or external one like "If I accomplish it, I'll be approved doing the job I want". The ideal situation is when you have both internal and external reason. Nevertheless in the short run, I think, you can easily work with just one of them.
And it also works not to postpone everything on the very last day. If you do so, there is higher chance to quit. Just as you have been doing small piece every day.
And last but not least - the more time you spend with your thesis, the more interested it is. So you can be highly motivated from the first moment or you can invest a lot of time into the activity and motivation will follow. All this because after a lot of time with your thesis you don't want to throw out all your effort, so you (unconsciously) convince yourself that the activity is interesting.