The fourth of the five Yamas is brahmacharya, which translates often as celibacy or continence. This can be debated on many levels and some of the older discussions go into the withholding of seminal fluid or feminine sexual energy and how it can be translated into prana – life force.
Many yogis and religious practitioners (e.g. pastors, rabbis) are “house-holders” – that is they practice their faith or their path, but in the world, as mothers and fathers and parents. It is not necessary to withdraw completely to live a life of faith, as a Yogi, a Buddhist, a Christian etc.
So, in a broader context, I think this Yama can be thought of as acting with restraint. Conserving one’s energy, eating in moderation, mindfully managing your emotional and energetic resources.