There are two aspects of who we are that require cultivation and improvement. The first, are skills. Being a better speaker, being a better author, being better at running fast.
Then, there are attributes. Courage. Perseverance.
These can be tricky. Even when we are able to convince ourselves that the human brain is truly malleable and that we can do anything, oftentimes we still don't do it.
Because we don't wanna.
Or because we're scared.
Or because we'll do it tomorrow.
This is why I recommend taking martial arts so often. It really cultivates the ability to do what we don't want to, to do what we're scared of, and to do it now. (I'm sure there are other activities that do this as well, what do you use?)
So, if you want to do the impossible, and you know what skills you require, but you're still not putting in the time & effort required to attain those skills, I'd take a good look at your attributes, and sign up for the activities you require to attain the attributes you need to tackle the decade(s) of skill acquisition you must do to achieve the aforementioned impossibility.
Here are some ideas:
I was equal parts terrified and excited to become a father, so I jumped out of an airplane. Cultivating courage is actually remarkably simple. Just do something that terrifies you. If something is too terrifying, feel free to go the slow route and build up to it, but, honestly, if you're on a time crunch, jumping out of a plane is really efficient.
Perseverance / Integrity.
Treat every word out of your mouth as a promise you would die to complete, and pay really close attention to what words you say for a month. "Sure, I'll call you tonight.", "see you at six?", "Sounds like a good book, I'll read it." -- whatever. Pay attention, and treat each one as a do-or-die agreement.
Step two: Only make promises you intend to keep.
Step three: promise to do things that will move you towards your goals. Start small, build upon your successes. Promise to do ONE push-up every day. EVERY DAY. Even if your arm is broken, you do the fucking pushup. Even if you're tired, or sick, or late, or hungover, or WHATEVER. You said you'd do it, so you do it.
If necessary, create contingency plans so horrific that you'll be forced to follow through. Eg: Write a $1,000 check to someone you hate, and give it to someone who you trust to mail the letter if you fail to (whatever) by (date).
Procrastination / Taking Action
Baby steps. Just do a little bit, right now, and don't stop. Like the push-up example above, habits naturally expand. It isn't just cigarettes and booze that multiplies through repetition. Push-ups do, too.
Have all the attributes you need? Get yourself some leet skillz and do the impossible!