These are some phrases that have helped me get through some tough times, and that I've been able to say to others to help them with their times too. So if you aren't feeling all that great, take a look at some of these, maybe they'll apply to you too. Most of these are my own works, if they aren't, then I'm sorry but more than likely I won't be able to give you original credit.
"Bad things happen to good people, because it is the bad things that make us good people". Seriously people, if you've had a bad life, then never forget that it made you who you are, whoever and whatever you might be.
"Things will always end, it might not be the one you want, but soon, you'll see it was the best one possible." I've been through a fair few endings, like the time I lost my first girlfriend, but over time, I've come to see that it really was the best way for things to go. Since then I've reunited with Jesse, by far one of the coolest people on this planet, and one of the best people I know in general.
"Just because you can, doesn't mean you should, and just because you should, doesn't mean you can." I'm pretty sure this is one I came up with myself. We all find times when there was something we could do, but that doesn't mean it should be done. If it's something you can do, you have the power to not do it to. As well, just because you should do something, doesn't mean you have the power to do it, if you feel you really should do it, work and become what you need to be to do it.
"They try to bring you down, because they can never reach your heights." I did borrow this one, and sadly I can't credit the initial author, because I don't know who it was. If someone is bringing you down, remember that you can, and will, rise above it all, and to not go down to their level, you'll be no better than them.
"Without evil, there can be no good" Just because things are going bad, doesn't mean that everything is bad, if you look hard enough, you'll find something good going on, and without bad, you wouldn't have good, you would only have things, and the good, would lose all it's specialness. I've been through some bad times, but I've always had something good with me too. Also don't forget just because something is "Dark", that doesn't make it "evil".
"Your past made you who you are today" I've said something like this earlier, but this just reinforces it really. No matter what happened in your past, it made you who you are, and there are some people who wouldn't change you for anyone in the world, even if you don't know it.
"Good things come to those who wait, great things come to those who make them happen" If you want something you consider "great", something you really want, then go out there, and make it happen. Nothing is going to happen if you aren't going to make it.
And that's all I can think of for now, maybe I'll come up with some more later, just remember, you're never truly alone, and as far as I know, there is no such thing as true rock bottom.