Why did Hashem give us all the Mitzvos, does he need anything from us?
The Ramchal and all the Tzadikim explain that Hashem created the world ONLY to be able to bestow His good upon us... The Ba'al Hasulam explains that the evil inclination is nothing more than "the desire to receive for the self". This desire was implanted in us by Hashem in order to make us separate from him, and in order that he be able to bestow his good upon us. You can’t give something to someone else if he is really YOU. He has to be separate from you before you can give him something… So how could Hashem give anything to anyone? After all, in essence, everything in the universe is Hashem! Our bodies, our minds, our hearts, and all our belongings, are really Hashem. So he gave us a desire to receive. The only thing that separates us from Hashem is this "desire to recieve", which G-d does not have. This is in essence what makes us "creations" of Hashem, and not just a part of him.
However, at the same time that this "desire to receive" is necessary for our "existence" (otherwise we would just be part of Him and not separate), it is the "opposite" of Hashem -because Hashem has no desire to receive anything. Hashem has only a desire to "give", and we exist only by virtue of our desire to "receive". And being opposite of Him does not allow us to become truly close to Him. Because in spiritual terms, the more similar you are to something, the closer you are to it. And the more different two things are, the farther apart they are. There is no “distance” in Heaven.
So what is our job? We can't just negate the "desire to receive" or we would cease to exist as an entity separate from Hashem. Also, if we destroyed our desire to receive, G-d would no longer be able to bestow his good upon us, which was the whole purpose of creation! So the Ba'al Hasulam explains that our job is not to destroy the "desire to receive" but rather to elevate this "desire to receive" to the point where we want only to receive for Hashem's sake and not for our own sake. The more one trains himself to emulate the attributes of the creator, the closer and more similar he becomes to the creator. By receiving only to "give" to the creator, we achieve the best of both worlds. Not only can G-d bestow his good on us, but we don't feel the shame of being different and separate from the creator through the receiving, since we are receiving only for his sake. This allows G-d to bestow his good on us, because the pleasure we receive is still enjoyed, but the enjoyment is for the sake of the great King, and not for the sake of the "self".
And ultimately, this also makes the enjoyment much greater in the end actually, and that is why we need to work so hard to get to that point. G-d wants our enjoyment to be infinite, and if the enjoyment was only for the "self" it would be limited to the capacity for enjoyment that we were created with. Once a cup is full, it simply can’t receive anymore. So if the taking is for ourselves (the cup), so then once we got all we wanted, it would be all over. However, if our enjoyment is for the sake of the King, then the greater the king is in our perception, the greater the enjoyment is. And since the greatness of Hashem has no limit, so too our enjoyment will have no limit. In the world to come (and some Tzadikim reach this level even in this world), G-d keeps revealing a little bit more of his greatness each day, and this in turn makes the pleasure that they receive from G-d more pleasurable each day, since their receiving is for the sake of a King who never stops getting greater in their eyes!
But this type of receiving (for the sake of the king) is a very high level, and in order to reach it one must first be willing to forgo any receiving for the self at all. For example, if one fasts a whole week, then maybe on Shabbos he will be on the level where he can eat a few bites and enjoy it truly for the sake of Hashem. The more we are willing to give up our desires for Hashem's sake over the course of our lifetime, the more we will one day be worthy - and ABLE - to accept all the good Hashem wants to give us for HIS sake. And this is MUCH more pleasurable than if we received it for our own sake.
And that is the secret of the Yetzer Hara, and of all the 613 Mitzvos.
It's all for US - if we do it for HIM.