A slow start to the NASCAR Cup Series season — two crashes and an engine failure through six races — has Bubba Wallace looking internally for the steadiness he needs to pull himself out of this early slump. It was his mother who encouraged Wallace to do some self-reflection. “It’s day by day, right? Just got to be a better version of myself,” Wallace told The Associated Press this week. “My mom had said to me, ‘You know, if you want things to change, you got to change yourself.’ So I’m just trying to change myself and be more active, working out, eating better, and just trying to have a…