The Founding Fathers understood that there is a natural tendency for those who seek power to be reluctant in exercising it with prudence. They limited the powers of the presidency for this very reason. George Washington was our first president and an optimal example of the role because he accepted power reluctantly and was willing to cede it when it was necessary to do so. Had he been elected, Ron Paul would have been a contemporary example, a man of independence and principle, who only sought to obtain the office of the presidency in order constrain the power of the executive.
It took four elections of FDR before anyone even considered term limiting the presidency through the Constitution. And we live in an era where the proliferation and overuse of executive orders has expanded the scope of presidential power in a way that the founders neither foresaw nor would they have been likely to support. The further we move away from the intended limits on the Presidency, the less likely we are going to like the results.
Check out some our favorite quotes on the subject: Founding Fathers Quotes on the Limited Executive Powers of the United States Presidency at Ammo.com.