Guitars can be real bitches sometimes. Or rather its the player, but still I blame my guitar for a lot of things I can't do. Don't over-do it at first. I remember when I had my first guitar lesson (and last, because I was scared of the guy) in fourth I played with my thumb. I must of played for a few hours one day, and I developed a huge blister on it. I quit for the time being and wouldn't pick it back up until sixth grade.
What brought me back was listening to my brother play. I recommend you try to meet other musicians, and listen to them when you get frustrated.
Getting guitar lessons is also a good idea. A teacher will keep you dedicated, and also it makes learning a lot easier for most.
Practice everyday, for a set amount of time. Don't just play 3 hours one day, then skip the next two day. To develop nerves in your hands you must practice everyday.
BLAH BLAH BLAH thats all I have to say... for now.
If your looking for easy stuff to play songs off Jewel's first album, Pieces of You, are good and a lot of people recognize them. Some of my best memories are playing Jewel songs in front of the middle school to crowds.