This is the one I personally struggle with the most. It is highly coupled with your perception of your personal comfort zone. For example, if I think I'd be happier if I went out and met more people - but I'd rather sit on the couch tonight - that's partial insanity - you will always be afraid of doing those things you are too lazy or afraid (note: lazy and afraid is worse combination) to do.
And if you were say to actually drag yourself to the event but completely went into wallflower mode when getting there, you are proving partial insanity again (e.g. being non-social again) with the added weight of 'why did I bother'.
How to break this vicious cycle? Basically you have to suck it up and be social, not be seeking any particular form of reaction - e.g. goal is literally to introduce yourself/meet people not to have a deep conversation with them. Letting go of attachment to outcomes but initiating so there can be a potentially positive outcome. Really, it goes back to #3 Being Present with whoever you are with.