The Lord says : Live the life of Karma Yoga. That it good enough. May you become one for whom karma done for 'Me' is the ultimate - Matkarma paramo bhav. It is the ultimate in the sense that it is the means that he commits himself to for the antah-karan-shuddhi required for Jnana. Knowing what is it to do the work for the sake of Lord is very much necessary.
Is it that like a master needs the services of his servant? The master gives the orders, telling exactly what has to be done and the servant obliges in return for some payment. Both stand to gain from the transaction. Does the Lord also tell you to do specific things whereby he is going to accomplish something? Does he expect to benefit from your activity? If so, he is not Ishvara. Doing something for the sake of Lord cannot be for his benefit because Bhagavan is always Poorna, complete. He has all that one could wish for in absolute measure. So, it is not for his sake. Suppose you do it for your sake. Then it is not karma-yoga. Doing karma for Lord's sake is doing it as an expression of your devotion to Him. This is dedicated to the Lord. Doing work for the sake of the Lord is an attitude and that is what needs to be developed.