The latter do it out of love, knowing that I am put here for the defense of the gospel. (Philippians 1:16, ESV)So, the one group that have become more confident to share the Gospel are motivated by love, specifically a love for Paul. They love Paul so much that when they find out he has been imprisoned for the defense of the Gospel, it motivates them to share the Gospel themselves.
One could ask, what motivates you to share the Gospel? But a more significant question to ask would be in regards to who do you love? Are there currently any heroes for the Gospel in your life that you love? As they share the Gospel, and go great lengths and endure sacrifices to make it happen, does your love for them motivate you and give you the confidence to share the Gospel yourself?