The most effective motivation is intrinsic: how to achieve it

Nothing can force us to do something. And even if it does provoke action, it will have a temporary effect.
Only intrinsic motivation works in the long run. This is the same as WANT, period! And then it's not a search for "motivation" - how can I force myself to do what I need to do now - but a search for HOW to do it!
How do you find that same WANT?
1. Admit to yourself that all the reasons you are giving yourself right now "to make yourself sound good" are lies. If it were a reason, you would have achieved your goal long ago... and if you haven't, then the bullshit you've voiced is convenient, not the truth. What is voiced is what does not motivate.
2. Start looking for it. If you want to, but the reason doesn't work, you need to dig deeper. It's not cool to admit it, it's not decent to admit it, the reason may be funny, scary, or more global. But it is there.
3. If you want change, get ready to admit to yourself what is wrong now. What really matters to you.
Although there is one more thing. When we don't need to achieve a goal to be able to justify other problems in our lives, the opportunity to suffer officially and voice it to ourselves and others.
So the question of change is "do I really want to or don't I want to?"