half a dozen useless things to know:
when you feel useles, you should go to bed and wait for tomorrow. there will always be something useful to do then.
when you feel tired, you should try to sleep and wait for your energy to come back - painfully slowly, but it will eventually come back.
when you feel like there is something missing, you should try and find something you now have, and tresure it, because you never know when that will be missing to.
when you feel there is nothing more to do, you should rest your mind and soul. your body will tell you there is always something left to be done.
tomorrow is just another day. making it paradise or hell is up to you.
you're never absolutly useless, you're never too tired, there will always be something missing and something to be done.
nobody really cares but you. and even you shouldn't care that much.
time to go to bed.