The sun shined bright over the first day of spring football practice, but a gloomy cloud loomed over a position with the announcement that Matt Lentz will give up his football career.Lentz, a junior who was in the midst of switching from safety to linebacker, has decided to end his football career due to repeated bouts with concussions, head coach Joker Phillips announced Wednesday.”It breaks my heart because I was a huge part of getting Matt here,” Phillips said. “Knowing how much this program means to him and his family and for him to have to give up football …”Lentz, who stood on the sidelines of Wednesday’s practice with shorts and a sweatshirt on, will file for medical scholarship and join the UK staff as a student-coach.The loss of Lentz creates even more instability at a position that faced a myriad of questions heading into spring practice. The losses of Micah Johnson and Sam Maxwell to graduation (and presumably the NFL), have opened up two starting positions at middles and strongside linebacker.Lentz was expected to make a push for time at strongside.”One of the things we were trying to do was get some experience and some more depth at that position, which was the reason we moved him to that position, which was the Sam linebacker,” Phillips said. “It does (weaken the position), but the game goes on, and Matt understands that. Life goes on for him. We’re just excited about getting him to be a part of our staff.”Lentz is scheduled to graduate in August after three years at UK.