Yoga Sūtra Chapter Two verse 38

ब्रह्मचर्य प्रतिष्ठायां वीर्यलाभः ॥३८॥

brahmacarya-pratiṣṭhāyāṃ vīrya-lābhaḥ ||38||

When established in conservation,
vigour is attained.

brahmacarya - study of the Veda; the state of an unmarried religious student, a life stage; conservation; state of continence and chastitypratiṣṭha - established; standing firmly, steadfast; point of support, centre or base of anythingvīrya - vigour, power, potency; heroism, prowess, valourlābha - attained