在活动开始前锻炼几个月对你是必要的（翻译成英文）

It is necessary for you to exercise for several months before the activity.

You must start to exercise a couple of month before the event.

上海灵格风英语

it is necessary for you to do some training for a few months bofore the activity

it s necessary for you that practicing for months before the activity begins.