The reason you're self-obsessed is probably because you're obsessed with yourself. In practice, that means you're thinking about yourself. If you're thinking about yourself, it is probably because, when you start thinking about yourself, you carry on, rather than stopping.
The way to stop being self-obsessed is to stop thinking about yourself when you start thinking about yourself, which requires two things: spotting when you're thinking about yourself and then stopping it and starting to engage mentally and practically in something else.
So, ask, when you catch yourself thinking: am I thinking about how I can serve God or am I thinking about me?
If it's the latter, switch to the former. Try this for a year, then get back to me.
The way to stop being self-obsessed is to stop thinking about yourself when you start thinking about yourself, which requires two things: spotting when you're thinking about yourself and then stopping it and starting to engage mentally and practically in something else.
So, ask, when you catch yourself thinking: am I thinking about how I can serve God or am I thinking about me?
If it's the latter, switch to the former. Try this for a year, then get back to me.