Gurudev, it is said, "Sa tu dīrgha-kāla-nairantarya-satkārāsevito dṛḍha-bhῡmiḥ". What is the exact period of dīrgha-kāla for me?
Dīrgha-kāla means don’t be in a hurry. It is said that one should not be in a hurry. That is why, the moment you say, "I am going to continue doing this for a long time", your anxiousness to finish it and get the result of it is gone.
Satkārāsevito means doing something with honor, respect and dignity, and not just doing it for the sake of it. People sometimes whine and wail while doing things, that is not satkārāsevito.
Dṛḍha-bhῡmiḥ means becoming stronger -- so when you do something without being in a hurry, with honor and respect, then that action becomes stronger and you become stronger.
You have to keep doing it till you feel there is no need to do it anymore.