You can suggest someone to do something that will be good for everybody, especially for that person. If they listen, great; if not, it's their luck. You tried, but they are not ready to have that.
But if that person is someone near you, you can't just let things go. You keep asking, requesting, reminding them again and again. Some may call it nagging. But you just want good for them and all. You just have to keep trying with the hope that someday they will understand or just listen.