From what I’m getting, you see the end point of major goals other people had, and you wonder how you could ever do anything like that.
What you need to do is turn that into a main quest line. In a video game (most of the time) you don’t start with “kill the big boss and save the realm” but every little thing progresses you to that point. The first thing you get as a goal is something stupid simple and abstract like Equip your sword and block some arrows. Eventually all the little side tangents culminate in “Kill the Boss, Save the realm”.
So try to use that principle in your life. Ask yourself a question, what do I need to do right now to do “XYZ”, come up with two things that would help you accomplish it. Now ask yourself, of those two things, is there anything I can do within the next 5 minutes to make that happen. If your answer is no (let’s be honest it most likely is), split each of those tasks into two things that will help you accomplish that minigoal.
Eventually you will have broken the tasks in two enough times you can find your “Equip your sword, Dodge some arrows” and start crawling your way up that quest tree.