There is something to be said for natural talent. It can make starting and learning something easier, but it does not make you the best in your field. There is something to be said for intellect, but being smart does not guarantee success. Skills can be learned, knowledge can be gained but to do that we need perseverance.
The ablity to keep working when things get hard, to press on when we are tired and to keep fighting when we feel beaten is the surest path to success. If we do not falter in our efforts to change, to grow, to hold to those New Year's resolutions, then we have no choice but to succeed.
Think of that - as long as we keep working and trying and do not give up the only outcome we can expect is success. We have no reason to fail unless we fail ourselves. The going may be slow, we may feel like we are walking in place, but as long as we keep picking up one foot and putting it in front of the other, as long as we keep pushing we will make it. Slow is not failure. Stopping is.