While I was listening to a guided meditation by Jon Kabat-Zinn (who is a Native English-Speaker) I bumped into an expression that appears to contain a sort of inversion in an affirmative sentence. I've looked it up in the Cambridge Grammar Reference online and it seems this is something not linked to the presence of be likely to.
Only if you know, or even suspect that it actually does, are you likely to have enough energy for the discipline of formal practice.