TLDR; Motivation is a push against inertia, so it's counterintuitive to wait for it. You have to be a little spontaneous, and actually make it a habit to gain motivation, or find external motivation through parents/friends/commitments.

What is Motivation?

Okay, so now starting with the base question: What is motivation? I think a good place to start here is with most peoples dilemma, not being able to find motivation, and therefore never starting something. The way I see it, in most cases this would mean motivation is a push against ones social inertia, in one way or another. Let's look at picking up your trash for example. There is a great reason to pick it up, but some people just don't because they aren't "motivated to". This applies to almost any case, all the way to not wanting to learn something, which is the fundamental idea that there is no intrinsic reason to do it.

Now after defining it, let's take a look at most peoples reason to not do something, which happens to be "not motivated". Since we've defined motivation as basic social inertia, it becomes apparent that motivation can come from 2 ways, spontaneity, or through external means (a push from someone else, or to meet a goal). Spontaneity is a great way to try many things, and to be motivated to do "stuff". It could be almost anything they want. The second means can be seen in practice often when parents try to push small kids to do activities, which they may not be motivated to do at first, but after time they start to like it, and are motivated.

This leads to the greatest sin, waiting for motivation. Since motivation is a push against inertia, by waiting around and building habits, you actively make it harder for yourself to get motivated, by gaining inertia. This often leads to a cycle of regret, where you wait for the perfect motivation to do something, but end up never doing it, or just forgetting about it all-together. A great way to imagine this, is to think of humans as advanced dogs. We love to follow patterns and ruts, but if we ever want to break the rut, no gut feeling will tell us, because internally we love these ruts. It really is a funny cruel way for life to act, but in the end, that would mean the spontaneous win out, while the people who wait for the perfect second end up failing.

So what?

So! How do we end up gaining motivation, and doing things that we want to do? One way is to become spontaneous. Act on every desire you have, and when you feel like something, just do it! It's a funny thing to say, but most often, the cure to motivation, is to just do it. You'll find motivation as the "inertia" to do the task lowers, basically meaning as you find it becoming a rut/habit (In a funny sense, that makes motivation counterintuitive, but meh). The only way to build spontaneity, is to be a little spontaneous in a sense (It sometimes doesn't even have to come from spontaneity, some people find it in motivational music or speeches).

The second way, is to find it externally. This could be a whole range of things, but the one I find interesting is to have a friend motivate you. This can be seen in many areas to work, like studying, where most people like an "Hours" type group, where they check in every hour or so, give progress checks, and share screens the entire time. I think this could be applied to a whole range of areas, with people reminding you to try something new and stick with it. Personally, this works with me by making commitments to show people things, which motivate me by not wanting to flake on them. Really, any means of motivation aside from yourself should work.

Now with your newfound knowledge what shall you do? Climb Mt. Everest maybe? Take on a pack of ravenous wolves? Take out the trash? Whatever you do now, just make sure to never wait for motivation to do anything, but try to apply some of the methods I said above. You might even learn to incorporate tons of cool new habits, and isn't that really what motivation is for?