12:6b If the gift is prophecy, that individual must use it in proportion to his faith. 12:7 If it is service, he must serve; if it is teaching, he must teach; 12:8 if it is exhortation, he must exhort; if it is contributing, he must do so with sincerity; if it is leadership, he must do so with diligence; if it is showing mercy, he must do so with cheerfulness.
Paul gives us a sampling of the variety of functions in the body, and as Bob mentioned, this is not a complete list — in fact a full list can’t be found in scripture anywhere. We should look at how God has wired us and allow ourselves to be put at God’s service and the service of others accordingly!
Not only does he encourage us to find our niche, but he also encourages us to show excellence in what we do. Notice how verse 8 addresses both the attitude as well as the dilligence with which we serve! The body doesn’t achieve its potential if the parts are not fully functional!