People don't often bring up the subject of "self-discipline", perhaps because they themselves have firmly established it as a habit. I, however, am one who does return continually to the subject because it is something that eludes me. But from today on, I will try my best to establish it as a habit in spite of whatever embarrassment I may feel over the many public resolutions I have already made.
I made lots of suggestions. Your actual mistakes were:
"one of their habits" (plural)
"I am one", not "I am the one"
spelling: "embarrassed"
"no matter HOW embarrassed I HAVE felt after HAVING promised"