yeah the reason for this is simply that you have no distractions from the thoughts that are clearly always there. i am just like you, and i'm very aware of my situation, but fixing it is another deal altogether. patience, essentially, you have to hope that there's a distraction, in the form of purpose, self worth...etc, and whatever purpose you seek is different for everyone, and to be honest, i don't know what mine is, but i'm progressing down the right path. it is hard, because what you're waiting for may never arrive, there are no guarantees.
the stage that i'm currently at in my personal situation, may sound odd, but trust me, it's very effective.
my feelings of depression, worthlessness, regret were all within me, caused by outside influences. the result is alot of inwards directed anger at the regret, self worth, disappointment. i'm aware of what's happening to me, which is how i found methods of using the anger more constructively. there's nothing wrong with harbouring anger (provided it's justified) and i realised that the way i treated my self was actually absolving the outside influences from any responsibilty for what i've become. and i don't deserve that.
after this realisation, i'm now able to redirect a large portion of anger outwards, driving me towards removing those outside influences. it is currently my purpose in life at the moment. essentially, anger and rage is the reason i get out of bed every day, instead of staying put and wallowing in my self pity.
i do this in the hope that life is markedly improved on the other side of those influences. this may not be the case, but it's a goal to aim for, a reason to live and breathe. if it's not better on the other side, i'll have to re think, re plan, whatever, but i'll cross that bridge when i come to it. nevertheless, if i'm not 100% better after i've overcome these influences, at least i have overcome them, and i have no doubt things will become clearer once i'm free of them, and life will improve, even if it's only by 1%. progress is progress.