Treatment for Stretch Marks on Tummy?

I have stretch lines on my whole tummy area and the skin will not tighten. I have had this since my birth of my first child at age of 19. I am now 43, I would like to do something about this.

I am very self concious about it. I am in no way over weight but can not get the outer skin to tighten or the stretch line to fade, can you help me please?