I think what you have written is very good. I think explaining your personal triumphs and showing your passion for education and growth is extremely important and acknowledging where you were and why and how far you have come and how you got there and the work you put in is important. It is also important to explain to show why that will not diminish when the stress of Grad school weighs down on you. How has the fire in your belly become permanent why wont it dissipate when you have work and school and family and everything else going on....what has changed that will keep you pushing through and keep you focused on your education.