God uses all His people, we just have to be willing and then act. We all want to be useful in God's kingdom, and God wants us to be useful. In fact He expects us to be useful. It is no good praying and asking for God to use you if you are not also willing to act. Like the invalid man at the Bethesda Pool in Jerusalem (John 5). He was required to act, to do something. In his case it was to trust Jesus, pick up his mat and walk (what incredible faith, given he had been lame for 38 years), and then to sin no more.
Older people are so incredibly overlooked in Western nations like Australia. This is folly! Older people have lifetimes of experience and wisdom which young people simply cannot have. They should in reality be paid more for their services. Yet the reality in our world is that they are often overlooked and go to waste in their older years.
That does not have to be your reality however! There is much to do and "retirement" does not have to comply with the "norms" of society. Orbus volunteers John and Sue Steendam are two good examples of this at Orbus. In their 70s these two faithful Christians continue to seek to do the will of Jesus in their older years. Praise God!
Faith's Checkbook by C.H. Spurgeon
"Go ye also into the vineyard; and whatsoever is right, that shall ye receive." (Matthew 20:7)
"Yes, there is work in Christ's vineyard for old bodies. It is the eleventh hour, and yet He will let us work. What grace is this! Surely every old man ought to jump at this invitation! After men are advanced in years nobody wants them as servants; they go from shop to shop, and employers look at their gray hairs and shake their heads. But Jesus will engage old people and give them good wages, too! This is mercy indeed. Lord, help the aged to enlist in Thy service without an hour's delay.
But will the Lord pay wages to worn-out old men? Do not doubt it. He says He will give you what is right if you will work in His field. He will surely give you grace here and glory hereafter. He will grant present comfort and future rest; strength equal to your day and a vision of glory when the night of death comes on. All these the Lord Jesus will as freely give to the aged convert as to one who enters His service in his youth.
Let me tell this to some unsaved old man or old woman and pray the Lord to bless it for Jesus' sake. Where can I find such persons? I will be on the lookout for them and kindly tell them the news."