Psalm 71:18

And even when I am old and gray headed, O God, do not abandon me, until I declare Your (mighty) strength to this generation, your power to all who are to come. 

Our lives are meant to be a testament to the power and strength of God on this earth. Our testimony filled with the good things God has done in our lives will speak to those who do not believe in Jesus. Even though we age, it doesn’t mean we stop talking about all the good things God has done in our lives.