We have a few tips for you to help you overcome this problem. It doesn't matter whether you want to learn a new instrument, stick to a training plan, study for exams or learn to juggle; the tips are applicable to all areas:
You reward yourself
Yes of course, the classic. The only thing is that it really works. Set yourself a goal to do/eat something great or do something else as soon as you have completed the task. It's important that you don't become weak and indulge yourself beforehand, otherwise you'll have a counterproductive negative experience and it will be even harder to stay motivated. A little self-discipline is a must.
Increase situational interest and personal significance
Let's be honest: we simply don't do most things because we have no interest in them. We've probably all been in a situation where we've thought to ourselves: I really have zero interest in what that lecturer up there is babbling on about! As soon as this thought flashes up, our attention is usually completely gone. So you have to try to find out why this topic is important to you. If you realize that what you've learned helps you with your hobby: Great! If you think to yourself: "I just have to pass the damn exam if I want my degree", then that's at least a start.
Learning and performance goal-related self-instatement
The principle behind this tip is actually the simplest of all. You want to be able to do what you have in front of you! Rocking the oral exam because you can do everything is a super good feeling! This also applies to other things you want to do. Be honest with yourself when you ask yourself whether you can already do something, because you probably want to do well!
Environmental control
Okay, that's pretty self-explanatory. If you want to stop smoking but still go on a smoke break with your buddies, the whole thing becomes much more difficult. Control your environment so that there are as few temptations as possible to break off your plan. Read through index cards in the pub...you'll notice that yourself, won't you?
Set sub-goals
Another suggestion that everyone has heard, but that doesn't make it any less effective. If you have a big mountain of work ahead of you, set yourself milestones, because if you only see the big picture, you're much more likely to give up. It's best to combine these stages with the reward strategy, then you'll soon be able to look at how much you've already achieved instead of just seeing a big pile of work in front of you.
Use social media
You don't have to go through this alone! Your fellow students have to do it too! Let friends and family help you with your plans. Others can support you professionally and emotionally if you're not up for it or feel completely overwhelmed.