The most important requirement to serve God, is to be willing to lose ourselves in His Work. He asks that we serve with all out might, mind, heart, and strength. In a way, He is saying that because everything we have is because of Him, if we have a desire to give back, this is how.
Now behold, a marvelous work is about to come forth among the children of men.
2 Therefore, O ye that embark in the service of God, see that ye serve him with all your heart, might, mind and strength, that ye may stand blameless before God at the last day.
3 Therefore, if ye have desires to serve God ye are called to the work;
4 For behold the field is white already to harvest; and lo, he that thrusteth in his sickle with his might, the same layeth up in store that he perisheth not, but bringeth salvation to his soul;
It is hard to put all our might, mind, heart, and strength in the service of God because we are in a carnal state in which we lean into tempration and sin. However, we are not hopeless thanks to Jesus Christ who allows us to have Grace.