Few things in the world are more powerful than a positive push. A smile. A word of optimism and hope. A "you can do it" when things are tough.
Money cannot buy peace of mind. It cannot heal ruptured relationships, or build meaning into a life that has none.
If I had to select one quality, one personal characteristic that I regard as being most highly correlated with success, whatever the field, I would pick the trait of persistence. Determination. The will to endure to the end, to get knocked down seventy times and get up off the floor saying, "Here comes number seventy-one!"