syntactic analysis - Can you make this sentence clear?

I insist on putting this never-before-heeded advice in my math syllabus every semester (this is only my third one). I often obsess about the way I write things and I actually re-read it myself this time and realize that it's probably not good English, and certainly not understandable. I could not figure out a nice, concise way of stating that third sentence (the one I put in square brackets, []).

Please can someone suggest a good, concise (but not terse) edit for the sentence in square brackets which would be clear to college freshman who are in a basic skills (that is, high school level) math class?

How to do well in this class: ...

3. Do all of the homework as soon as possible. Do the homework to make sure you understand the underlying concepts. [You will not learn what you need to know from me in lecture – not because I’m such a lousy lecturer, though I might be -- but because you only learn math by doing it.] Ask for help when you cannot understand a problem.

Thanks.

P.S. You are now probably the only people, other than me, to have read it.

P.P.S. "Concise" means as short as reasonably possibly so that the reader will still understand it (and I can fit my syllabus on 2 sides of a paper). "Terse" is shorter than than "concise".

Edit: All the answers were helpful (even the one inexplicably given a down vote, which I cancelled). I used a combination of them:

3. Do all of the homework as soon as possible. You learn math by doing math. You will learn the concepts in lecture. But you will only learn all of the detail by doing the problems (despite my peerless lectures!). You will be expected to know the material from each lecture by the next one.

Answer

How to perform well in this class...

Complete all assignments as soon as possible. This will assure you understand the underlying concepts. You will learn concepts in the lecture, but you will only fully understand them by practicing those concepts through completing the assignments. Above all, ASK QUESTIONS when you cannot understand a problem.

I am not sure what level you are teaching towards, but one suggestion I have is NEVER criticize yourself towards your students [...not because I’m such a lousy lecturer, though I might be...] stop that! If you don't have confidence in your abilities, how do you expect your students to? Everyone has room for improvement, this much is true, but don't start them off thinking that you can't lecture, its self defeating.

Good luck!