S. Arshi Ji
Welcome back and trust you will continue and share your understanding of gurbani with us.Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/37550-which-is-more-important-simran-sewa.html
Arshi Ji my understanding of gurbani reveals 'gurmat's evergreen unique message is 'eh kar kariah so eh kar paey' thus it dismisses interpretation of 'dhur' blessed from the beginning or concept of brought forward blessing of previous life. Thus 'dhur' stands for inner voice(antar atma) or that pivot around which our thought whether of 'manh' or 'gur ki matt' revolves. Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=37550
When gurbani says 'tu karta karna mai nahi' it is out of humility guru sahib is telling otherwise everything is done by us and us only whether reflected with gur ki matt or manh ki matt.
I hope I clarified your query.
Mohinder Singh Sahni