What you have to do is to remember that even in your darkest hour you have to look for the light at the end of the tunnel. Just keep striving towards your goals and know that in the end if you stay true to yourself, everything will be okay in the end. You can't just go saying that things are bad, because, you know, they might just turn out to be good again later on. Which is good. Although, those good things might be bad later on in life, if you catch my drift, because there's more than meets the eye beneath the surface.
So you've got to look on the bright side and not just believe that the grass is always greener on the other side because there are plenty more fish in the sea and you only live once. Even if everything looks bleak, remember that the greatest light comes from within and at the end of the day, that's all that really matters.