Colossians 3:23-24, "In all the work you are doing, work the best you can. Work as if you were doing it for the Lord, not for people. Remember that you will receive from the Lord, which He promised to His people. You are serving the Lord Christ." Scripture encourages you and I to do our work and serve as unto the Lord. Whatever we choose to do, whether teach a class, help someone, or physical labor, it would do us well to keep our heart in the right place.
Often, we complain when we begin to work for the Lord. We grow weary and tired, sometimes feeling as if we are the only one working. But Scripture teaches that we serve faithfully for the Lord's sake, not for the praise of others. Then, in the end, our reward will be great and it will come as a direct blessing from the Lord.
Therefore, do not keep record of your work. Do not count others who fail to work. But instead, stay focused on your purpose. Work and serve only for Christ. And He will give you a rich reward.