I used to bristle when I heard terms like this. It sounded corny, cheesy, something a slimy marketer would say all the while never truly being truthful themselves. These past few months though I have come to look at this phrase in a completely different way.
What this phrase really means is believe in who you are and what you do. That's to long for a sound bite and if you are just doing a job for a paycheck then it doesn't really apply to you but if you are your own boss then if you don't follow this you are sunk.
Since I have narrowed my focus, got serious with who I am and what I care about a lot of obstacles have just fallen by the wayside. The path is clearer, this doesn't necessarily mean its easier but at least a lot of peripheral nonsense is disappearing.