Regret is actually the first step to tshuvah. If you've done an honest assessment of the past year, you're probably already there. The second step is rejection, or to stop doing the wrong action. No amount of regret makes a difference if you don't change. The third step is resolution, the determination not to repeat the act again.
Habits are so hard, sometimes seemingly impossible, to break.
Suppose you found out you were going to die a few days after Yom Kippur. Stop for a minute and really think about this possibility. One of our High Holy Day traditions is asking God to sign and seal our names in the Book of Life, instead of the Book of Death. But if we took this Jewish tradition to heart, we could really turn our lives around. If we knew we were going to die soon, many of us would live our lives differently.