Peter proclaims the Gospel. No special words. Just the basic message. He also shows how Old Testament is fulfilled in Jesus quoting Psalm 16. That’s the fruit of reflection on facts.
Learn for yourself the basics of the Good News. I’d recommend the book: Case for Jesus - Brant Pitre. Or listen to the 1hr lecture that is in Formed.org http://watch.formed.org/the-case-for-jesus
This spiritual reading would be a great use of your free time, or even as part of your prayer and meditation time, but not replacing it. Remember, God wants not just your mind, but your heart and soul as well. Getting excited and inspired by some part of the Good News, which this book or lecture could do, is an important part of being a strong witness to Jesus.
Slowly Peter’s understanding deepens through more praying and reflecting on Scripture and sharing with the other Apostles and other followers of Jesus. Our faith is deepened only when we use it. We can’t expect it to grow on its own.
This is what happens to the disciples on the road to Emmaus. Their faith is only deepened by encountering Jesus. They were open to letting God speak to them as indeed Jesus generously does even in disguise along the way. Their understanding grows through this sharing. Then when they finally realize the Lord is with them and not just a random traveler, they must run back and return to Jerusalem to bring the Good News to their brothers. They become evangelists these two disciples, Cleopas and the unnamed one. They simply tell their story. This is what God has done in my life.
All of us are called to do the same. Perhaps an easy thing is sharing how our prayer life helps us grow in love and peace each day. Or How God answers our prayers sometimes in big obvious ways. Or just sharing something that built up our faith.
It also means deepening our faith by being with each other as Christians or by sharing virtually with each other as these times require.
Finally, about this deep truth that Jesus was made known to them in the breaking of the bread. It is not a coincidence that Jesus disappeared from Cleopas and the other disciple when their “eyes were opened.” This isn’t a sign that Jesus abandoned them but rather a fulfillment of the word at the end of Matthew’s Gospel: “Behold I am with you until the end of the ages.” His presence was still there, but it is transferred into the Eucharist. nowadays when we are stripped from gathering for Mass and receiving the Eucharist, We are called to realize the same truth but in some ways in reverse: instead of realizing Jesus is among us and then having his presence vanish, we must see our hunger and longing for the Eucharist as a testament to the truth that Jesus is really here.
It was not until they recognized Jesus in the Eucharist did they realize that He had been present in all of their lives. I believe that deepening our faith and understanding of the Eucharist would be a profoundly fruitful use of our time away from the Mass. But above all, to know Jesus, alive and present in your lives, in your mess, redeeming it, restoring it. This is the primary role of the witness. And the world today needs witnesses. Let us learn from Peter and from Cleopas and the other disciple how to witness to Jesus present among us.