A Sikh who treats Nitnem as a chore has already lost it. Nitnem read at speed, with the mind elsewhere, to discharge an obligation, is not Nitnem. It is recitation. The Gurus did not give the Panth recitation.
The word combines *nit*, daily, and *nem*, rule or vow. The daily vow. A Sikh who keeps Nitnem keeps the vow of daily contact with the Guru's word. The vow is the standard. Until the standard is felt as standard rather than as burden, the practice has not yet matured.