You will never be as young as you are again right now, your toddlers, children or teenagers will be a day older tomorrow, a little taller, a little wiser, a little changed. They will never be as little as they are right now.
I have three of my own little boys. My oldest recently turned six and I am not sure where those years have gone. All of a sudden, he is six and in Prep, he's not home with me each day anymore, I will never have that time with him again. But I have photos to look back on and they bring back the memory associated with it. Those photos are my link to his babyhood, toddlerhood and early childhood. They will also become his link to those moments too.
Why a professional session? First and foremost, because it puts you in the frame with your children. We are lucky today, in that photos are much more accessible to us, a quick snap on an iPhone and we have frozen that moment forever, but often we aren't in these, we take them but are rarely in the frame with our kids. In a professional session you are there with them. Your children do not care if you haven't had that haircut or haven't lost that 5kg. They only care that they can look at beautiful photos of you all together. That they see the joy they bring you, that those smiles and laughter, cuddles and love are all for them.