giving up an addiction depends on the level of the addiction. for some people they can just stop it if it is in its early stages and not so serious , for others doing some activity like going out and doing a hobby will help and for the serious problems they should seek professional help or some sort of counseling
Well giving up an addiction is hard, but remember first people have to accept that they have a problem.
Then they need to get either help or be hard for them self. Stop it 100% by being disciplined.
Or even better find some opposite thing to fight against their addiction.
Reverse psychology is very effective.