Living from the outside-in is an endeavour to placate an all-consuming feeling of emptiness with stuff from the outside.
Stuff like the accumulation of material possessions. Stuff like compliments, status, and affirmations.
Living from the inside-out is recognising that fulfilment and abundance exists within, and that we manifest our inner value into the outer world. It comes with no need for the external permission, qualification or the approval of others. It comes because we know we have everything we need to play our bigger game.
When you know this and when you own it, you will present to the outer world with the energy and joy this understanding brings. It is a self-fulfilling state that compounds and amplifies what is possible for you.
You can choose to rely on others to validate you or you can choose to validate yourself from within. Fulfilment, in order to be both authentic and sustainable, must be an inside job.