Expanding my capacity

Riley has a cough assist machine that we have to use on her twice a day (and some times as many as 6 times a day when she is sick). The machine does what its name implies, it assists her in clearing her lungs by blowing in positive pressure and then sucking it back out. This pressure allows her lungs to expand to a capacity that she is unable to expand them to on her own, but she absolutely hates it. She squirms and cries and sometimes even throws up because she gets so upset when I do her treatment with it, but it has huge overall benefits for her respiratory health. So even though it kills me to see her upset, I do her cough assist treatments at least twice a day, everyday. Tonight right after I finished a treatment she looked up at me and smiled with her face all red from crying and a big alligator tear still rolling down her cheek - and I though "this is how I am supposed to act". Why is it that I can do such a horrible respiratory treatment to her all the time and she still smiles at me afterwards, but when our heavenly Father tries to do something that helps us to expand our capacity we get angry, blame Him, cry our eyes out, and we don't smile at Him even when it is all over. This is what Christ meant when He said to have faith like a child - to believe that your parents are doing what is best for you and to just simply trust and follow. Sometimes I want to slap James for saying "Consider it pure joy, my brothers, whenever you face trials of many kinds, because you know that the testing of your faith develops perseverance. Perseverance must finish its work so that you may be mature and complete, not lacking anything" (James 1:2-4), but the truth is he couldn't be more right. We need to smile during uncomfortable and hard situations because we know that there WILL be good results once it is over and we would not be unable to attain those results, that new level without the current difficult trail. So, thank you Lord for daily expanding my capacity, I am so grateful for your unfailing love and commitment to never let me stay as I am.