Approach without excuse simply means don't accept excuses for not approaching.

I've caught myself umpteenthousand times saying 'Nah, I won't bother with her, she's too <insert perceived negative characteristic here>'

And eventually, it becomes a crutch for getting oneself out of approaching.

By saying 'without excuse' I mean approach everyone. Fat, thin, fit, ugly, young, old, whatever. Open everyone, and decide later whether you want to push or not.