Life is challenging. Every day is a new challenge, it's up to you if you fail or succeed in those challenges. Will it be hard? Yes. Will you want to cry? Definitely. Will you always feel 'up to the challenge' or motivated? No.
The good news is every day is a new day, a chance to start again. If you messed up yesterday just forget about it, learn from the mistake, and make today better than yesterday. About the crying, it won't be all the time, but there will be days when it seems like to much and you just have to cry, once you've cried it all out you'll feel better. Maybe not 100%, but it will help take the 'world on your shoulders' feeling away. Don't forget if you are blessed enough to have good friends and family to talk to them. Let them encourage you and possibly even help you.
And most important don't forget to pray. God loves you and would never put more on you than you can bear, but sometimes (as you know) it feels like there's to much for you to handle, but He wants us to ask Him for help, He loves to help us, to show His love for us even though we aren't worthy. We will never be worthy, but we are to strive to be the best that we can be so don't let not being perfect stop you from trying.