The first step would be to identify the undesired behavior you wish
to change.
The next steps are the trickiest and depends on many factors. This
include developing a conscious and deliberate plan which includes 1)
the ultimate goal, benchmarks (smaller more obtainable goals to reach
the ultimate goal), 2) the steps to the first benchmark, 3) the rewards
to reinforce desired reactions which approach the steps to the first
benchmark, and 4) the criteria to use to mark progress.
It may be helpful to work with a partner (someone else with the same
phobia or undesired behavior) as a support person or a mentor (someone
who has done it or has some counseling background). This is a very difficult
strategy to accomplish alone.
Reinforce the positive steps away from the undesired behavior and
steps toward the desired behavior with the selected rewards.
Monitor your progress. Change the size of the steps, the rewards,
or the benchmarks if any do not seem to be working.
You may hit plateaus or periods of backslides. Accept them as a temporary
setback and identify potentials of self-sabotage, negative self-talks,
or situations which should be avoided for the time being. Make a conscious
decision to continue with your plan (or modification of it).
This may be a life-long "work in progress" if you are trying
to change a deep-rooted fear or a behavior which feeds an addiction.
Again, this is very difficult to do alone. You may need to work with
a partner, mentor, or counselor.