It seems that Superman's parents may have been the reason that he's been able to keep up his never-ending battle with Lex Luthor. As Mon-El discovered, Jonathan and Martha Kent's unwavering support were probably the only thing that's kept Clark from throwing in the towel.
The classic origin of Superman may start with baby Kal-El being rocketed from the dying planet of Krypton, but it sure doesn't end there. After making his way through the universe, the Kryptonian infant crash-landed in Smallville, Kansas where he was found by the kindly couple Jonathan and Martha Kent. The influence of Superman's parents helped mold the powerful youngster into the hero he was destined to become. And while Clark would ultimately leave Smallville to share his amazing gifts with the world, he always made time to return home to keep Ma and Pa in his life.
And it turns out, Superman kept his adoptive parents involved for reasons beyond love. As the Daxamite hero Mon-El found out, they may have kept Clark from throwing in the towel. In Superman #694 by James Robinson and Renato Guedes, Mon retreats to the Kent farm after escaping from Project 7734, a military operation spearheaded by Lois Lane’s father, General Sam Lane. As the hero Superman entrusted to keep Metropolis safe while he was in space, Mon-El is kicking himself over falling into an obvious trap set up by Lane. He confides in Martha that he doesn't think he's fit to be a replacement for Superman. Ma Kent tells the young hero that Clark, too, faced moments of doubt about his superhero work, especially when Lex Luthor routinely got away with his crimes. Martha relates the same platitude that Jonathan would always tell Clark to keep him fighting the good fight.
Martha isn’t lying when she says Lex Luthor has rarely paid for the evil acts he’s brought upon the world. For all the times the villain has tried to kill the Man of Steel, Luthor has gone on to run his companies and even become president. Such a foe’s resiliency is no doubt a blow to Superman’s morale, but in the face of despair, Ma and Pa Kent were always there with the words of inspiration their son needed.
Even for someone who can stop a bullet or bench press a planet, there are some things even Superman can’t defeat, like a flawed system that allows a villain like Lex Luthor the ability to walk free despite his history of crimes. Such injustice would make anyone question the value of trying to make things better, even a superhero. But Superman's parents knew that someone with gifts like Clark's couldn't afford to squander them. By being honest with their son, Jonathan and Martha gave Superman the hope he needed to continue fighting evil, no matter how much effort it takes. Lex Luthor may continually challenge Clark, but thanks to Superman's parents, he'll never give up trying to defeat his enemy.