செயலற் றிருப்பார் சிவயோகம் தேடார்
செயலற் றிருப்பார் செகத்தோடுங் கூடார்
செயலற் றிருப்பார்க்கே செய்தியுண்டாமே
This literally means, 'only those who do not do anything are the ones who will realize the truth'. To me, he does not mean the tamil phrase 'gundu chettila guthara otrathu' (GCGO), meaning just idling all your time without doing anything concrete. Actually, such people are doing lot of things. Their minds are constantly at work trying to find ways to 'enjoy' their time in whichever way they like. But, Mr. Moolar is not talking about GCGO.
I believe, what Thirumoolar is referring to is an internal state where there is no unnecessary urge to do anything. Basic livelihood things will be done but otherwise, there is no urge to do anything. For most of us, it is next to impossible to even sit simply for sometime. That is one major reason why we find tempers getting frayed very often in queues. This internal state of 'stillness' where there is no urge to do anything for oneself is indeed enlightenment. Then, there is all the life energy to work for the society as one deems fit. And that, is YOGA. Karma Yoga!
Thirumoolar also says such people do not mingle well with the world. This is true as their ways are seldom understood by trivial analysis.