Vyaasa's comment on YS II 1, first clause:
naatapasvino yogaH sidhyati |
We think, without sandhi that would be:
na + atapasvinaH; yogaH sidhyati
Well, tapasvin is:
tapasvin a. distressed, miserable; devout, pious, doing penance; m. & f.
{tapasvinI} an ascetic, a religious man or woman.
So, a-tapasvin prolly is the opposite of tapasvin.
Now, as a substantive that could mean something like "non-ascetic".
As an adjective it could mean e.g. 'not-distressed', "unmiserable"(?).
Thus, Vyaasa could mean something like: someone who is not an
ascetic, shall not be successful (sidhyati) in yoga; or:
yoga without suffering is not possible...