PHILADELPHIA — Another workout nearing its end, Paul Kroll pulled off his sweat-soaked shirt and placed a towel atop the canvas of the ring. Kroll lay on the towel as his 4-year-old daughter held his feet, pulling himself forward while a trainer counted his sit-ups. If Kroll — a rising boxer from North Philadelphia who fights Friday night on Showtime — needed any more motivation, he received it each time he lifted his head from the canvas and locked eyes with his daughter. Jasmine’s birth in 2017, Kroll said, was life-changing. Her arrival provided a clear perspective when it was desperately n…