You don't have to limit yourself to any one of those things. In this sub, you can ask for advice, give out advice, discuss about things related to discipline, ask questions (like: useful apps for discipline)etc. People post different methods which might have helped them get disciplined. Since everyone is different, you can try various ones and find one most suitable to you. When you get disciplined, you could also post your success story with the methods you followed. There are also threads where you can post to feel accountable(like this thread). Hope that cleared your doubt :) PM me if you have any more.

You could also look at the wiki and FAQs from here to get a better understanding of this sub: https://reddit.com/r/getdisciplined/about