I've been pulling apart this question or idea for quite some time now -- as we are saved by grace, where is there room for the law? It's not that Jesus came to throw out everything, rather to "add to it". How are we bound to follow rules when they aren't a measurement for what we recieve.
An idea later hit me. We, rather I, should not look at it is, "Well, if I do this, then I'll get this reward". Instead, I need to do what God tells me to, attempt (and I will fail many times) to follow the commandments merely out of love for God. That what love is -- doing what someone else wants rather than what we personally want.
"Jesus came to serve and not to be served" comes from the Bible. Now if I could only get myself in gear to do the same.