How many times were you planning to study but you postponed it because "you weren't feeling like it." You lacked motivation until external motivation struck you. Usually, the external motivation was provided by the approaching deadline.
Fear of deadline can be very motivating, but is it the right motivation source? Can't we do better?
Motivation is not enough
The expression "Not feeling like it" suggest that motivation works like emotions. That's the problem.
It is a problem because emotions are temporary. Even strong emotions like love or hate are not constant. When you are in love, you feel the love when you see the loved one or think of them. It may be quite often, but it is not all the time. Seriously. It would be impossible. You can't think about two things at the same time, and I bet you think about other stuff too, even when you are deeply in love.
So motivation is an emotional state. At least, internal motivation works like an emotion. External pressure, unfortunately, seems different. We won't use external motivation, though. I want you to do things you want to do, not to be forced to do them.
Make a decision
The first step to do what you need to do, even if you are not motivated, is making the decision.
There is a massive difference between "I have to do something" and "I decided to do something." Even if you have decided to do it because you must.
Now, tell me, are you a dependable, trustworthy person? Probably. It is difficult to imagine a person who admits they are unreliable. We are going to use it to our advantage. We will use it because you can't say "I'm trustworthy," and, at the same time, say "I decided to do it but I won't."
Only one of those sentences can be true. Which is it?
Are you thinking of an excuse right now? Valid excuses exist. Usually, those are related to medical problems or emergencies. However, most likely, the excuse you are thinking about is not in this category.
Trust the process
You have made a decision. You are a reliable person. And you don't have a valid excuse. What now?
This will sound like lame coaching, but... what is the simplest thing you can do now to make some progress?
Seriously. Instead of big motivation and putting enormous effort once, we need a process and tiny actions every day.
What do we do when we want to lose weight? Do we go to the gym once and do a 12 hours workout? Or do we exercise one hour three times a week for a few months? The same happens with learning. A one-time effort is not enough.
Sit down. Open the learning materials and spend 25 minutes studying them. Studying! It means you need to focus. You need to think about the topic. You must try to understand it. Did you get stuck? Spend those 25 minutes looking for the explanation.
Are 25 minutes enough? Hell no. Take a short break and do it again. You may repeat it as many times as you want or just stop after 25 minutes. But remember to do the same the next day. Small steps. Every day.
What if you need to learn it until tomorrow and it is too late for taking small steps?
I don't know. I don't specialize in miracles. I am here to get huge results in the long run.