Although you don't have control over some issues of life, but you are the total sum of your choices. Life happens. It is what you do with the experiences that matters. According to Nassim Nicholas Taleb “A Stoic is someone who transforms fear into prudence, pain into transformation, mistakes into initiation, and desire into undertaking.”
Click this link to see the graphical illustration of what I am driving at in stoic sport.
detailed more on stoic philosophies.