You’re never to old to serve the Lord, or too old to change direction at His guiding.
Throughout the Word of God we see that the Lord calls people of all ages to serve Him.
Samuel was just a child when the LORD called him to serve Him. Moses was 80 years old when he led Israel, by the Hand of God, from bondage in Egypt.
I too tried to use the, “I’m too old to serve the Lord!”, excuse. I was 38 years old when He called me to full-time ministry. I had a career and was quite happy serving Him in my local church in Maryland, but He called me to surrender to the church planting mission field of Utah.
If you’re not serving the Lord in some capacity in your local church, find a place to serve Him! If God is changing your direction in the later years of your life, follow Him.
They shall still bring forth fruit in old age; they shall be fat and flourishing; (Psalm 92:14)