Serve God is not limitation of age

Exodus 7:1-25
The Load let Moses like God to Pharaoh, and Aaron will be Moses prophet.
Moses say everything God command he.
God will harden Pharaoh's heart, and though God multiply miraculous signs and wonders in Egypt.
Egyptian will know I am the Load when I stretch out my hand against Egypt and bring the Israelites out of it.
First miraculous sign is Aaron's staff becomes a snake
Second miraculous sign is the plague of blood, all rivers, canal, ponds and all the reservoirs were turned to blood. Egyptian could not drink its water.
Pharaoh's heart turned hard, he did not listen to Moses and Aaron.
These 2 signs did in front of Pharaoh, Egyptian magicians did the same things.
Moses and Aaron did God's command were 80 & 83 years old.
Why?
God talked to Moses and Moses said everything God command him, so Moses did like God to Pharaoh. Moses is God's ambassador.
God begins a series of judgments which will teach pharaoh and his people who the Load is.
The magicians may counterfeit, but they cannot countermand.
To do God's work, no limitation of age.
How?
All of the Christians are the ambassadors of God, I should show the witness in front of people around me.
Magician does counterfeit but cannot countermand.
Not matter how old I will be, when I follow God's decrees and laws, I will be a good servant of God.
Serve God is not limitation of age