The first thought that popped into my head for that question was

NOTHING!

But, as some have experienced here, there are some approaches that seem to have worked. The main thing is, they have to be at a juncture in their lives to even begin to let any other thoughts in. They have to be fed up with a few things.  

"When the pupil is ready the master will appear"

.........and not until then, usually.

Only those who will risk going too far can possibly find out how far one can go.

t.s.eliot