Kacey has no interest in rolling over or sitting up. I've tried and tried and before she rolled over…

Kacey has no interest in rolling over or sitting up. I've tried and tried and before she rolled over on her own a couple times or even tried. Now she doesn't try. She will sit up till she realizes I'm not holding her and she throws herself back. Or after 5 minutes she starts crying. I just want her too do it! Lol