Christians should have active minds.  God does not intend us to be passive or indifferent to Him or to our human circumstances.  If we take the preceding verses seriously (1 Peter 1:3-12), we know that we should live each day joyfully waiting for Jesus Christ to come back, trusting God's written Word.  Yet in times of suffering, troubles and persecution, some are tempted to give up the struggle against sin, the world, the flesh and the devil.  They put their minds into neutral gear, ignoring God's commands, hoping the battles will go away.

But this verse says our minds should be alert and ready for action (Romans 12:2).  What sort of action does Peter mean?  It is not to invent solutions to our discomfort.  It is the intentional action of removing whatever is unnecessary to focus on Jesus.  Hebrews 12:1-2 uses the metaphor of an athlete removing clothes that would impede running, ‘Therefore, since we are surrounded by such a great cloud of witnesses, let us throw off everything that hinders and the sin that so easily entangles. And let us run with perseverance the race marked out for us, fixing our eyes on Jesus, the pioneer and perfecter of faith. For the joy that was set before him he endured the cross, scorning its shame, and sat down at the right hand of the throne of God. Consider him who endured such opposition from sinners, so that you will not grow weary and lose heart.’  

Peter says the same.  Keep focussed on the day when Jesus Christ returns, and the reward He will bring to His faithful people.  This focus is also an active renunciation of all that would get in the way.  Our minds are to think about how we can select-out some things, habits, relationships, ambitions and desires - choosing to renounce them with God’s help.  The lifestyle of a soldier, athlete and farmer must be disciplined (2 Timothy 2:3-6) to achieve the intended results.  Likewise, the Christian.  That choice is not made for us, we need to make it for ourselves.  As we do, we can be confident that Jesus Christ who saves us, will sustain us.  The Father who has prepared an inheritance for us, will enable us to receive it.  The Holy Spirit who gives us joy will also give us self-control (both are fruits of His presence within each believer (Galatians 5:22-23)).  But our responsibility is to apply the self-control to our own lives.

Every day, we need to think carefully about how we can honour the Lord.  This will not necessarily make life easier for us now (it may make life much harder), but it is a clear decision knowing that we will be accountable to Jesus when He returns.  Passive minds do not care, but those who do care what Jesus thinks will set their minds on getting ready for His arrival.  If our working day requires us to think carefully about management, processes, profit and quality, how much more should we be concerned to have minds focussed to think through how best to please the Lord (2 Corinthians 5:9).  You can assess how much this matters to you by reflecting on how much you want God to help you to be self-controlled for His sake.