In fact, without renunciation (tyaag), nothing [no spiritual development] can happen. Renunciation of what? Complete renunciation of illusion (bhranti)! Complete renunciation of the ego (ahamkar)!! Complete renunciation of the my-ness (mamata)!!!

The One whose ego (ahamkar) and my-ness (mamata) go away completely, is considered a complete tyaagi (one who has renounced worldly life). 

In renunciation, egoism is present; [but] there is no egoism in saiyam (a state in which there is absence of anger, pride, deceit, greed and attachment-abhorence). 

Saiyam (a state free of anger-pride-deceit-greed, attachment and abhorrence) cannot be attained through egoism. Renunciation can take place through egoism. In renouncing, doership is required, there needs to be a doer of the renunciation.

Renunciation (tyaag) should be natural and spontaneous. [That which is to be renounced] should fall off on its own indeed.   

You will have to suffer the consequences of all that you renounce. Is it in our control to renounce (tyaag)? Is it in our control to acquire (grahan)? That is actually dependent upon one's merit-demerit karma (punya-paap)!