I think the within stuff if poorly interpreted by most. No one will be happy when their basic human needs, lots of them external, are not somewhat satisfied, we are social organisms and we also find nurishment from exterior sources.
The within part, the way I see it, is about whether or not you can use the positive external stuff to be content. It's like the difference between being in the middle of the desert with no food and water anywhere and starving/dehydrating because of that and being close to a perfectly good river in an area with fish and edible plants and being unable or unwilling to make use of those resources.

Most people won't be able to live emotionally healthy and content lives completely alone all the time, you can't not be lonely by always solely with yourself, for ex. But if you do have people around and the real opportunity to connect to them, if they try to connect to you and you are unable to do it or unwilling, then you do need to work with your inner self.