Is said whole, with nothing composed onto it and takes no だ／です, so there are no forms to conjugate.
無理をする
muriwosuruto push oneself too hardexpression
Example sentences2
体調が悪いときは無理をするべきではありません。
taichou ga warui toki wa muri o suru beki dewa arimasen.
When you're not feeling well, you shouldn't push yourself too hard. neutral
無理をするより、少し休んだほうがいいよ。
muri o suru yori, sukoshi yasunda hou ga ii yo.
Rather than push yourself too hard, you'd be better off resting a little. casual