"So Moses and Aaron did just as the LORD had commanded them. Moses was eighty years old and Aaron was eighty-three when they spoke to Pharaoh." vs6-7
God can use us in old age. He's not bound by time.
First, you don't have to regret the former years, and live in sorrow. You have learned your lesson now.
When Paul told the shipmates that they should have listened, he told them to be comforted now [Acts 27:21-26]. They left the shipwreck with a greater knowledge of God than before the storm. Their disobedience made way for future obedience.
Likewise, Moses ran away when he was forty [Acts 7:23-29]. He did not waste 40 years in the wilderness. God used them to empty him of self confidence, which is necessary. The desert was Moses' school to learn about himself. Now, Moses is 80, and he is used. He could not have been greater.
Secondly, look at Moses as an example for you. We've squandered time, but it was not squandered, if God's called us now. We don't have to think about the years wasted. We can be fully used now and blessed because we're humbled. We don't have to think, I could have been great. We can be mighty in the Lord now.
We can preach now and pray now! We don't have to work up slowly. We can fully obey all the Lord has said and accomplish the present task. "So Moses and Aaron did just as the LORD had commanded them.”
Thirdly, be about the work. It's time to work now, the Lord is with you. Haggai 2:4 ‘Even so, be strong, Zerubbabel”—this is the Lord’s declaration. “Be strong, Joshua son of Jehozadak, high priest. Be strong, all you people of the land”—this is the Lord’s declaration. “Work! For I am with you”—the declaration of the Lord of Hosts.’ Deliverance is happening now. Set about the task God's given you, and He'll be glorified. Deliverance from Babylon proclaims the gospel. Recovery from falls and failures preaches Christ. People live messed up lives, and they need encouragement in grace, kindness, and repentance. Others are in bondage, and you can help them now by your experience. God is fully with you!
Finally, the gospel is full of power after years in the desert. Believe God now!