Can the mamas help me out!!

My boyfriend and I decided to try for our first baby! Does anyone have any suggestions I can start doing to prevent a saggy tummy after pregnancy? I know it’s bound to happen but would like to make it as minimal as possible ☺️ thanks in advance! Also any suggestions on good to know things that you wish you knew before or think that I just should know would be so helpful! I have no parents and am new to all of this so i really appreciate any advice anyone will give me about anything pregnancy/baby related!