I tend to agree with the principle, but there is one glaring problem with it. It doesn't take into account the external circumstances that may be extremely limiting on a person's life.

I remember saying something along these lines to someone many moons ago when I was at uni, how it is up to us how we view and accept our circumstances, regardless of what they are and how we got there. He said, "That's great for you or me as a white person with a middle class background and an education, but what about the woman in rural China who suddenly finds herself pregnant with a second child?"

So while I would encourage everyone (including myself, and I have) to look at their circumstances and make the best of the opportunities that are available to them in society (and in ours, there are many), it isn't, unfortunately, always that simple.