I tend to get deflated when I've done what is "the best I know how" and someone comes in and makes me do it all over again based on their thoughts and ideas. By the end of the day I'm hurt, pouting, and frustrated, all my energy is completely gone and I question if I want to keep going.
God's discipline is a little like that too. God's not going to leave you alone with stretching and growing you, it just doesn't stop.
You are much too valuable.
Let's make a perspective change here, let's take your view and help you see it another way. (I love when God does this to me, it makes me go from blah to AHA!)
What if that continual training means that you are going to improve your knowledge and ability. What if it is simply free education. What if the person investing in you believes in you enough to make you go farther. What if your negative reaction to the correction is simply because you don't believe in yourself enough to know that you really do have the ability to go much further than you are currently at?
Have a great day my friends, go out there and soak up all the knowledge you can gain.