It's weird to say "I am ambitious and I waste time vegging out watching TV" in the same breath– chances are the "I am ambitious" statement is really identity performance.
OP wants to be seen as ambitious (not just by his others, but by himself as well). It's a comforting narrative to hold, but it's also damaging (kinda like a cigarette addiction– you enjoy the pleasure of the cigarettes but you start noticing that your health is going downhill).
The gnawing pain that OP feels in his chest– I'm sorry that there's no nice way to put it– is the realization that he's a fraud [1]. It's the dissonance between "I am ambitious" and "I am wasting my time". One of those things have to go.
And we're all frauds to some degree, because we all tell ourselves stories about ourselves that feel good. OP is working himself up into a brilliant, painful frenzy, and in a sense it's likely that he enjoys it in a twisted sense– just like how some groups of people enjoy the drama of social relations, and keep perpetuating it.
BTW, just for fun (but seriously, too)– the most accomplished people like this tend to be writers. Balzac, Proust, Dostoeyvsky– all of them did this whole agonizing woe-is-me thing, or represented it powerfully in their work. OP, you might just make a great novelist. Write a modern day Lost Illusions with yourself as the title character, and you might just achieve the success you were hoping for!