Don't try to hard. Don't run against the wind. Someday you'll make it, even if you don't make it in this life. Trust Him. You may feel like this will never end but you can endure. It's better for you to keep working at it now than to face the eternal flames later. And really, there isn't very much that you have to "work at." Most of the work has been done for you. Just accept it. You've been given so much meaning. You have so much value. Do you not know this? You'll make it. Trust me. And even if you don't trust me on this, trust Him.
Also, know that there may be moments when you have to put your oxygen mask on first in order to make sure that you can help others do the same. That's okay. It's not selfish if it's necessary. What help would you be as a gasping body to the child seated next to you? If you do not care for yourself to a certain extent, you may be ill-equipped to care for others down the road; remember that.