Post Workout Soreness?

3

Hello! I've always been an athletic person, I have played sports and in general, consider myself fit. I recently started incorporating more strength training videos into my routine (instead of only completing HIIT). My first few strength training workouts I was very sore the next day, but now, I don't get sore anymore. I sweat like a pig during the workouts, but I'm not sore the next day. Should I be stepping up my workouts? Is this a sign that they aren't challenging enough anymore?

Thank all, I really appreciate it!!