What is our life when compared to eternity?

In a couple of days it will be 4 months since mom went home to be with her Maker. Wow, I can't believe how fast time flies! 73 years of her life here on earth are but memories in our hearts. Even still it bothers me at times. It's not the fact that she is gone that bothers me as much as that the time I had with her was short, like a vapor, quickly faded and gone.
I can't imagine the disciples only having 3 years with Jesus. And his mother only 33. At least I has 15 more years with ma, than Mary did with her Son.
What must have been going through Mary's mind? What was she feeling? It had to have been nearly unbearable to watch her Son go through such torture!
Watching our mother go through the coughing spells and difficult breathing traumas, and heart attacks and surgeries was not easy for any of us. And seeing her on the hospital bed while she took her last breath, had to have been even harder for my dad and sister. 103 years...sounds like a long time, but 73? But if we look at it in the perspective of things; what is our life when compared to eternity?