I think the first and most important thing is to realize that it is not in our place to change others.
Everyone has his/her own say in how he/she wants to lead his/her life. This includes his/her beliefs, lifestyle, religion, career choice, circle of friends, values, goals and dreams.
While we can disagree with the choices people make, and we certainly can let them know our unhappiness with what they do, we have to respect that it’s their life and it’s up to them to decide what they want to do. To the point where we want to “change” them, reflects a disrespect of who they are as individuals and what they stand for.
This applies to everyone – be it friends, family, or partners.
The bigger question is to ask ourselves – Are we okay with who they are? Can we accept them the way they are right now? If they are to remain like this for the rest of their lives, will we want to continue to be with them?
If the answer is yes, then the issue probably isn’t that fundamental. Don’t focus your energy on the things they do that makes us unhappy. Rather, focus on the things they do right that makes us happy – the very reason why we are with them to begin with.
At the same time, use those annoyances to improve ourselves. Behind every annoyance we have with others, reflects an opportunity for growth inside us.
If the answer is no, and that it’s a make-or-break factor (i.e. it’s a determining factor for you), then let the other party know, by way of an open, heart-to-heart discussion.
This means rather than simply tell the person what you are not happy with, let him/her know (a) how much this friendship/relationship means to you (b) the things he/she is doing (or not doing) that’s troubling you (c) what you’d like to see instead. This is first step, where you air your side of the story.
After which, comes the second step – which is to understand his/her point of view. Hear him/her out – (a) listen to what he has to say (b) understand why he/she does the things he/she does (c) understand what he/she would like, moving forward. This is a very important step – after all, the relationship is not just made up of you; it’s made up of you and someone else. This step provides the other party the space to express his/her views , vis-à-vis it being a one sided imposition where it’s just you speaking.
Then from there, you have the third and final step, to assess if things can be worked out or not.
Throughout the discussion, adopt an open mind. Share your views, but don’t impose them. Listen to what the other party has to say, and don’t shut him/her out.
Ideally, you should arrive at a solution that makes both of you happy – and not just you or him/her only. Any solution that only makes one party happy isn’t a solution – it’s a compromise. Compromises are short-term – they only stifle you and make each other unhappy in the long-run.
If a common solution can’t be worked out at all despite all efforts, then there’s no point in continuing on, at least not within the current definition of the relationship. In which case, you would have to define a new relationship dynamic; one that supports both your agendas. For example, when relationship partners switch to become friends, or when good friends drift apart, or when family members move out to get their own space, etc.
The important thing is that you should never remain in a relationship expecting the other person to change (unless there’s already a pre-agreement to do so, such as via heart-to-heart discussions above). Such a relationship will only make each other unhappy in the long-run, because on one hand, you are in the relationship in hopes of a change that may/may not happen in the future – and which certainly isn’t part of reality right now. This creates an ongoing tension, both inside of you and from you to the other party. On the other hand, the person is faced with the responsibility to live up to X expectations, when it may not be what he/she wants for him/herself.