Rejoice with those who rejoice, and weep with those who weep.
Being used by God to minister to others is one of the greatest privileges of a believer. And He's equipped you with all you need. You only have to be willing and sensitive to His leading. You also have the Holy Spirit. His ministry is to guide you into all truth, to bring to your rememberance the truths you've learned. God's truth sanctifies and sets people free. So, when you minister, ask the Holy Spirit to show you what truths the person needs.