How can you save a person who does not want to be saved or does not see the need to be saved?

Think you have a friend who has had a big problem for a while already. Be it drug addiction, depression, or any major problem you can think of. Many people have tried to talk to him/her and find solutions. Either he does not care, does not understand he is in trouble or does not see a point for him to get better and thus does nothing or even gets worse by the day. You see him wither away.

If you know for sure his life would be better if he acted differently how can you "force" a person to get better? ( If it is even possible).

Then you can also think this on a broader scale. I talked to few experts on health care field that what if there would be a place where people could be taken or could go in to voluntarily that is focused only to get people back to their feet in much more comprehensive way than anything there is today.

For example, a homeless person who used to have a good life is now in ruins and in brink of death. Suddenly men in white outfits come pick him up take him to a facility where he gets a normal day routine, exercise and counseling and all. After a year he is a changed man and thanks from the bottom of his heart that he was kind of forced to do a life change.(Someone who thinks this cost too much money can think now the person is a fully functioning member of society and can even pay a bit back from the work he will get, and personally I think its not even right to put a price tag for peoples lives