It is human instinct to seek advantages and avoid disadvantages.
If pain is more than pleasure,
How is it possible to stick with it?
The person that can hold to fitness all the year round, basically enjoy fitness process: the joy when running, the pump feeling when muscle contractive, the mental state that brings after motion is waited a moment.
If you can't enjoy it all and feel more pain, it's not far from giving up.
It's better to let yourself go and do something that makes you happy.