Pain v/s Gain
There is a common idiom in military parlance:
“The more you sweat in peace, the better you are prepared for war”.
Another common idiom in gym culture:
“No pain -no gain”
The nature of the universe (or any part of it) is such that any boundary can be extended by stretching ourselves a wee bit more and covering a little more distance.
Some “pain” (struggle/Effort) not only introduces you to a new threshold (temporary gain), but also strengthens your physical stamina and your belief system for further and bigger challenges.
In contrast, a life in avoidance of pain makes us lethargic and lazy, progressively unable to face even those hurdles which were easily overcome previously