Acts 28:16-20, 30-31 / John 21:20-25
If we were in a supermarket just to buy something, we might be tempted to browse around and see what else we can get.
We might end up getting quite a lot of stuff but forgetting to get what we actually wanted.
In that sense, a shopping list is important to help us stay focused in getting what we actually needed, and also to prevent us from going on a shopping spree.
In the gospel, Jesus had just commissioned Peter to take care of the early Church.
But just as quickly, Peter got distracted and was curious about the other disciple whom Jesus loved.
In a very firm and pointed manner, Jesus addressed the issue: What does it matter to you; you are to follow me.
In other words, Jesus was saying to Peter: Mind your own business, stay focused and follow me.
Even in the 1st reading, St. Paul did not lament about being in chains despite his innocence, but he took the opportunity to proclaim the Kingdom of God despite wearing those chains. He stayed focused on Jesus.
So Peter's distraction and Paul's predicament have taught us to focus our minds and hearts on Jesus and to follow Him.
Nothing else really matters.