The Greek verb gymnazo means to train or exercise — originally in the context of athletic training performed in the nude (Greek: gymnos). The word carries connotations of rigorous, repeated practice designed to develop skill and endurance. In the New Testament it is used both literally and metaphorically for spiritual discipline.
The New Testament repurposes athletic training language for spiritual formation. Hebrews 5:14 describes mature believers whose 'faculties are trained (gegymnasmena) to distinguish good from evil.' Hebrews 12:11 says that discipline 'produces a harvest of righteousness and peace for those who have been trained (gegymnasmena) by it.' 1 Timothy 4:7 commands Timothy to 'train (gymnazo) yourself to be godly.' The theology of gymnazo is that spiritual maturity requires deliberate, repeated practice — just as athletic excellence requires daily training.