Waiting for motivation to come by is a trap you will do well to avoid. You can take charge of your motivation using these few tactics. Let me know how they work for you:

1) Strategic self dialoguing: What you do is you look at students who are less bright than you are who are doing better than you, or those who you feel like you must outrank (surely there are some people in your program you don't like ) and you tell yourself: "See, even this guy/girl is doing it, when I am times better than they are", or "If they can do it, I am going to feel like crap if I don't do it too, so let me get started and overtake them for good."
You get the idea.

2) You set daily goals for the amount of work you are going to get done every day. For the first few days, don't aim too high. When you have the first few successes in your grab, it is going to feel quite good just showing up and getting work done. You are creating steady results and it is a matter of taking small steps that add up to create big results rather than trying to get it all done at once. It is more motivating and much simpler than trying to aim for exhausting targets and failing at them.

3) Make a list of fellow students who are quite ahead of you in terms of their studies, their grades and overall performance in this program. The kind of people you feel intimidated in the company of knowing how ahead they are of you in terms of the distance they have covered and how much you are lacking and have been left behind.
What you are going to do is, you are going to meet them or talk to them at least once every day. Just keep in contact with them. Just being in their company will want to make you try harder and join their ranks, because you don't wish to feel like you have been left behind and feel "separated".

You will have to overcome the inital discomfort that you may feel, but it will offer some incredible motivation to get things done. I say, do it!

That will help. Get in touch with me if you need anything. I am happy to help.