I don't know if other people think about this question, but I do often. I love what New Tribes Mission says to all believers in response to this question (from their website):
Am I called?
Yes. God's called all believers to "make disciples of all nations" (Matthew 28:19). So you need to discover what He specifically wants you to do. He's not hiding that from you; God desires to lead and guide us. You should spend time in prayer and in His Word, and seek godly counsel. And please consider this: You are already reading a website designed to help you take part in planting churches among unreached tribal people. Look for His guidance and follow His lead, one step at a time.