"It is written: 'I believed; therefore I have spoken.' With that same spirit of faith we also believe and therefore speak, because we know that the one who raised the Lord Jesus from the dead will also raise us with Jesus and present us with you in His presence. All this is for your benefit, so that the grace that is reaching more and more people may cause thanksgiving to overflow to the glory of God.
Therefore we do not lose heart. Though outwardly we are wasting away, yet inwardly we are being renewed day by day. For our light and momentary troubles are achieving for us an eternal glory that far outweighs them all. So we fix our eyes not on what is seen, but on what is unseen. For what is seen is temporary, but what is unseen is eternal." 2 Corinthians 4:13-18
For the most part I'll let this passage speak for itself. I want to just quickly highlight three things.
1) If you believe you should speak.
This doesn't mean that we'll all be the type to speak about our faith all of the time, but we can't speak about our faith none of the time. St. Francis of Assisi once said, "Preach the Gospel at all times and when necessary use words." We don't always have to speak to preach the Gospel, our changed lives will do it much of the time; but sometimes we will all be compelled to speak.
2) Don't lose heart.
Because of the hope we have in the resurrection we should not lose heart. From the moment we are born we begin the process of dying but we have already achieved eternal life, which is knowing Christ, if we have been saved. Because we have this hope we don't lose heart. Also, we don't lose heart because our suffering achieves an eternal glory for us. This is easier said than done, but rejoice in our sufferings because they pale in comparison to the glory they achieve for us.
3) Be heavenly minded.
Fix your eyes on what is unseen, what is heavenly. When we think with an eternal perspective we make better choices. The world thinks it's foolish to think about the unseen, but who's the fool? Pursuing an eternal glory is much wiser than pursuing something that is gone in an instant, like a vapor as King Solomon said.
Don't be afraid to speak about your faith. Don't lose heart. Be heavenly minded today.