What does the person have? Why is the person reluctant?
Find out the worst consequances that can happen if that person's condition is left untreated (Prefferably with pictures) and give it to them in a form of collage. Letting the person know that he/she may have only a couple of days to live unless they take some medicine may also help shaping their opinion to the positive...
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~