If you are thinking of taking it up yourself, always do a warm-up exercise before you run, don't go too fast at the beginning, and don't overdo it.

yourself 是反身代词，指"你自己"，用于强调动作的执行者就是主语"you"。 warm-up 是复合名词，由动词短语 warm up（热身）转化而来，指"热身运动"，即运动前为预防受伤而做的准备活动。 overdo 由前缀 over-（表示"过度"）和动词 do（做）组成，意思是"做得过多/过度"，在这里指"运动过量"。