When I feel I am a failure

Sometimes after a difficult week, I get down on myself and begin to see myself as less than I was the week prior. I think of all the wrong things I said, and the right things I didn't say. They way I brushed off a resident that could have used a cheering up. How I just talked about myself and my problems to a friend when I should have acknowledged his struggles more and tried encouraging him. I feel as if I am a bad RA for not always remembering to report the lack of paper towels or soap in the dispensers. I feel as if I am constantly being selfish for sometimes picking out my needs before a residents or focusing on my homework for a night as opposed to going to a resident's room and asking about her day. Basically, I just feel like a failure in my job and as a friend overall.
But you know what? God knew when he placed me in these situations that I was not going to do everything perfectly. Not even close. He knew exactly what it would be that I am struggling with and that sometimes I would choose avoiding the problem instead of facing it. He knew that I would fail.
But he chose to put me in the position anyway.
And that is encouraging. God wants me on my hall, knowing exactly how important I will be, even if I feel like I am a more negative influence than a positive one. If I never failed or sinned, I would not be in this position; I would be Jesus, dying on the cross. So thank You, Lord, for letting your son do that job, and giving me my job as challenging as it can be, so that I can fail but be comforted knowing that Jesus has already picked up my slack and saved me and taken my failures and made them perfect in Him. God will take the situations and sins I mentioned earlier and use them for my good and my residents'/friends' good. How amazing is that?
I now need to take this newfound encouragement and re-invigorate my passion for my residents and my job for next semester, and pray that God will use me all the more next semester. And to maybe humble myself and take less time to think of myself.