I am not very sure but I would probably use on the other hand or therefore.
I need to know what argument you are talking you are talking about to answer the question.
Answer:
1) slow down your pace.
2) slow down!
3) please slow down.
4) please slow down your pace.
Explanation:
There are quite a few ways to make this an imperative sentence.
By the way, you don't have to add "please" at the beginning, it just softens the sentence a little (it sounds less commanding)
