One of the most difficult things everyone has to learn is that for your entire life you must keep fighting and adjusting if you hope to survive. No matter who you are or what your position is you must keep fighting for whatever it is you desire to achieve.
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!