I'll be the first person to admit that there are some things I look at and think, "There's no way I could ever do that." Organic Chemistry and Calculus would be two of them. There is no way possible way that I would be able to do that. There are other things that I think the same thing of.
When God places something in my path that looks scary and challenging, I think, "There's no way I can do that." When I reach those places I often want to shut down and run the other way. Things like experiencing heartbreak, moving away from home for the first time, illness, death and even just getting through every day.
At some point during my sophomore/junior years in high school, I remember God leading me towards ministry. I vividly remember telling Him that He had it all wrong. (Can you imagine? Me telling the Creator of the universe that He had it wrong??) I thought that there was absolutely no way that I was meant to serve God in that way. I said, "You know what? I'll teach Sunday school. That's what I'm supposed to do." So, I did. I worked with the three-year-olds on Sunday mornings.
Coming into college, I felt the same tug on my heart from God that I was meant for ministry. Again, I thought, "Pssshh. He's got it all wrong." I'm not meant for that. I'm not good enough to serve God that way. Well, long story short - a year later I'm a ministry major. Look at that! God said that I could do it and here I am.
The thing about God, is that if He speaks it, it will happen. If He says you can do it -- You can!! That's the cool thing about God. You can do all things in Him. Philippians 4:13 says so. "I can do all things through CHRIST who strengthens me." You see, on my own, there is absolutely no way that I could work in ministry. There is no way that I would have gotten through my first heartbreak, and my second, and even my third. There is no way that I could have gotten through moving to college without Him. Watching loved ones go through cancer would have been impossible without the hope that I find in my Creator. There is no way that I could wake up every day and get through the day without knowing that God is holding me in the palm of his hands.
So, when you get discouraged, just remember that God is always there. He is always there to pick you up and say "You got this." Because, in God, you've got it all.