“G-d wants the heart,” the main point is the heart! Rabbeinu said: “Give me your hearts, and I will lead you on a new path.” Your hearts – the heart. And also, if a person searches for truth, he will find it!"
-Saba Yisroel -
Be whole hearted with the Lord thy G-d! Your life has a two fold aspect- what happens to you and what comes from you, what you recieve and what you produce, your lot and your actions. With both and with every fraction of both you must feel yourself immedietly under G-d. Your lot proceeds directly from G-d. So live your life directly for G-d-and wholly. G-d causes you to be born at such a time, such a place, of such parents, in such enviroment; He brings you into contact with such and such men, gives you such friends, such teachers, equips you with such faculties both of body and of mind, places you in such a position in life. He gives you all this as the means with which to carry out His will. Everything which falls to you you should fulfill with all that has fallen to your lot. 'Should' not 'must' for whether you will really fulfill it depends entirely on yourself. As the sages say: "Everything is in the hands of G-d except the fear of G-d", Everything is G-ds only the heart is yours.
-Samson Raphael Hirsch-
You see everything depends on the heart! Everthing! Whatever sitiuation you were born into poor or rich, good or bad, Jew or non Jew, G-d himself placed you there. To serve his purposes? what that is, you must pray to G-d and review your life and ask him the purpose you are to fulfill. So we learn from this, however the reason G-d wants the heart, is because it is the only thing you are free to give.. You see if G-d made a Jew a Jew and a non Jew a non Jew, the Jew sure can rejoice in being made a Jew, but he has done nothing to be a Jew it is what G-d has given him... You see this is why G-d wants the heart! Because that is the only thing he gave you as yours to give everything else was freely given you whatever your situation.
So you see whether Jew or Gentile or Noahide or even Nanach! It is your heart God wants! And this is above all service!!!!