One of the class projects was for us to remove the stop words from our speech by the end of the semester. We did this by all using recording software (had to submit either by cassette tape or wav/mp3) and answering questions such as "Do you want to live forever and why or why not?" by speaking for at least 5 minutes. These were our homework assignments.
We had to very consciously never use any stop words. We could pause the recorder if we had trouble thinking of what to say, but we could never say those words.
I was skeptical of the assignment at first but my class all agreed by the end of the semester that it made us much better speakers, simply learning to consider our pauses instead of filling the silence with "like" and "um".