I must say that although the piano is a very popular instrument, it is in no way an easy instrument. However, that is NOT a reason to give up on it, for there is so much that you would be missing out on. Practice truly does make perfect, and the more you practice, the better you will become.
Every time I begin a new song, I always find that I have a little voice screaming, "This song is way to advanced for you. Go do something else with your time". Do I ever think to listen to that voice? No. Do I ever grow frustrated while learning new songs? Absolutely. However, I find that when I am practicing, and become frustrated with a really difficult part of a song, walking away from the piano for a few minutes to calm my nerves will usually help. (A few minutes does not equal a few months, kids.)
Afterwards, I go back and I find the part to be much easier to move through. Otherwise, I repeat that difficult part over and over again until I get the knack of it. In terms of how long to practice: do not follow my practice times! My routine may not be helpful for everyone! Practice for at least thirty minutes to an hour everyday (I do strive to practice songs that I do with Agnes for at least fifteen to twenty minutes daily), or however long your teachers recommend. The reason I have such an unsteady method of practicing is because of my schedule, and because I juggle between songs with Agnes, and songs that I compose/improvise on my own.
If you find the music/exercises that you are studying to be boring, buckle down and keep practicing. Although you may not notice, the songs that you are learning act as stepping stones that gradually help you move into more difficult material. If you keep "walking along the path", you will be able to play anything that your heart desires in the future!