How do you keep pushing forward?

I am 57 years old and feel like my life is over. I have been successful and then burned my career to the ground too many times to count. I’ve literally made millions of dollars and have nothing to show for it. I lost this wonderful woman seven years ago, the love of my life. I don’t know if I’ll ever be in love again. I have three great grown children and a granddaughter to live for. I’m just so worn out with life and feel like just giving up.