Unfit: of a person 人 not in good physical condition; not fit, because you have not taken exercise 健康狀況欠佳;身體狀態差
The captain is still unfit and will miss tonight's game. 隊長身體欠佳,將不會出席今晚的比賽.

Mire: an area of deep mud 泥潭;泥沼
The wheels sank deeper into the mire. 輪子在泥潭中陷得更深了.
My name had been dragged through the mire(= my reputation was ruined). 我的名聲受到了玷污.
The government was sinking deeper and deeper into the mire(= getting further into a difficult situation). 政府在泥潭中越陷越深.

Stretch: an act of stretching out your limbs or your body and tightening the muscles; the state of being stretched 伸展;舒展
We got out of the car and had a good stretch. 我們下車好好舒展了一下身體.
Only do these more difficult stretches when you are warmed up. 要做了準備活動以后再做這些較難的伸展運動.
Stay in this position and feel the stretch in your legs. 保持這個姿勢,體會腿部繃緊的感覺.

Stroll: a slow relaxed walk 散步;溜達;閑逛
We went for a stroll in the park. 我們去公園散了散步.