To those who don't think they are strong enough--
First off, you are strong. Stronger than you think. Although it may seem like life is too hard to manage right now, it will get better. I'm a firm believer that life will not put in front of us anything which we cannot handle. So I think that most important thing we can do is to keep a positive mind and know that we can get through anything. Because once we find a way to battle through what life has thrown our way, we will emerge a stronger and wiser person. We are strong enough to do whatever we set our minds to, strong enough to reach our goals, strong enough to do whatever is necessary to find our happiness.
Life is literally a roller coaster, one day it will lift you up so high that you feel like you're on top of the world, and then the very next moment everything can come crashing down and fall apart. But that is also the beauty of life. I think that as long as we learn that now, we can then anticipate the lows and better prepare for them, we can become stronger so that one day they won't affect us like they once did. I think it's important to keep in mind the fact that nothing and no one is perfect. Everything is a work in progress, some are just better at hiding it.
But what I believe more than anything, is that one day all of our struggles will pay off. What life throws at us now will make us that much stronger for overcoming it. So no matter what obstacle life placed before you (like a failing exam grade, a break up after two years, or the death of a loved one) I believe it's important to take all of those struggles and turn them into learning experiences, study harder and devote everything you have to passing your next exam, finding yourself after it's been so long, or learning how to cope, I think it's the struggles which make us stronger. It's the strong people who get farther in life, so whether you're feeling low or feeling that life placed an unmanageable obstacle in your way, it's essential to remember that you are never weak, you are strong. And from this point forward you can continue to grow and become stronger.