Exercise while pregnant?

I have never been super into exercise, always had a high metabolism and whatnot so I just never really got into it. But ever since I got pregnant, I feel groggy most days and tired and just plain tired. Which I know is all normal for pregnancy, but my question is how many of you girls started an exercise routine while pregnant? and did it help with the constant tiredness and grogginess you felt everyday? I’m 21 and a half weeks along and really wanna get into it, just not sure how to start or the appropriate exercises I need to be doing.