http://www.buddytv.com/articles/2007-com icon/supernatural-interview-jared-p-4114 6.aspx

Interestingly, Padalecki expressed how he felt that his own experiences have paralleled his character’s life. He began the show at twenty-two and just recently turned twenty-nine. During a time when Padalecki felt that he had to do everything to further his career, at the time Sam was going through something similar. Now that he was a lot more calm and happy about being completely focused on the show, his character appears to have mellowed out as well. Padalecki definitely feels that he has ebbed and flowed with the younger Winchester.

I think the advice I would give to my character is to do exactly what we’ll see he’s doing, which is… it’s a marathon, not a sprint. Sam, for instance in season 4 when he was… you know, when the clock is ticking, Sam just starts making decisions and rushing things, and a lot of times it’s the wrong decision. So this Sam, that we see in season 7, is kind of learning to just, to breathe, to try to breathe and reassess the situation before moving forward. Hopefully he doesn’t bone himself. Or hurt himself anymore. I guess that’s a better way of saying it… more PC way to say it.