Srila Prabhupada wrote in one letter: "The point is to be engaged in doing something for Krishna, never mind what is that job, but being so engaged in doing something very much satisfying to the devotee that he remains always enthusiastic."
This is one of the great secrets of success, at least while we are still conditioned by the modes of material nature. Find out what you really like doing, what you have a natural talent for, and then to throw your whole heart into doing that very, very well. Many successful devotees have found a field where their natural strengths and abilities are exactly what is required to do the service and achieve the desired results.
You can also find a field in which you can do be totally absorbed. A service or area of endeavor that completely fascinates you, that holds your attention, that is a natural expression of your unique talents and abilities. When you are doing what you love to do, you can have a continuous flow of excitement, energy, and ideas to do it better and better.
Here are two questions for you. Number one, if you got a million dollars, tax-free, tomorrow, would you continue to do what you are currently doing? Number two, would you stay in your current service? These questions simply ask you what you would do differently if you had all the time and money you needed and you were free to choose your service or occupation.
Successful devotees, if they got a million dollars in cash, would continue doing what they are doing. They would perhaps do it differently or better or somewhere else. But they love their service so much that they wouldn't even think of leaving it or retiring.
One of the great responsibilities of your life, when you are surrounded by so many different choices of service, occupation and activity, is for you to find out what it is that you really love doing for Krsna and then to dedicate yourself to that field. And no one else can choose it for you.