帮忙翻译一句话，我心里没底

这个翻得我自己心里没底，完全还给英语老师了就是说他从19岁开始锻炼（肌肉），觉得对又觉得哪里好像又不对，My dad since he was 19 years old to start exercising ，求帮忙解答

告诉我选哪个最好，别写太难，看来我这照搬的翻译确实是错的.，我心里没底，求来个好人，我都分不清....你们翻译好多个啊上面这个翻译是我照搬人家的，把年纪改了，其他的没改，但是我自己改成he就行，主要是后面的

My dad started to develop his muscle at the age of nineteen.

你的译文错误太多，已经改进提升质量。

My dad started to exercise since he was 19 years old

My dad has been doing exercise since he was19.

My dad has started exercising since he was 19.

你好！ 锻炼肌肉 exercise one's muscle My dad had started exercising his muscle, since he was 19 years old. 如有疑问，请追问。