From the outside, Orthodox fasting and feast cycles can look like spiritual fussiness. From the inside, they are how the body learns to keep time with God.
What "Tradition" means
Capital-T Tradition (paradosis) in Orthodoxy is not "the way grandma always did it." It is the apostolic faith handed down — Scripture, the Creeds, the seven Ecumenical Councils, the liturgy, the lives of the saints, the icons, the prayers — preserved as a living whole. Paul commands it explicitly: "Hold fast to the traditions that you were taught by us, either by word of mouth or by letter" (2 Thess. 2:15).
Calendar
Some Orthodox jurisdictions use the Julian calendar (Old Calendar — Christmas Jan 7), others the Revised Julian (New Calendar — Christmas Dec 25). The Paschalion (date of Easter) is shared. The difference is more practical than doctrinal. Both calendars sanctify time — the goal is the same.
Fasting
Orthodox fasting is not penal accounting. It is bodily prayer. Roughly half the year involves some level of fast (Wednesdays, Fridays, four major seasons). The point: training the body so it doesn't run the soul. Fasting without prayer, alms, and forgiveness is, as the prophets said, useless (Is. 58). Fasting with them is medicine.
Why it all matters
Christianity is not a set of ideas to think; it is a life to live, with a body. The Tradition gives your body something to do — kneel here, fast now, sing this, kiss that icon, light this candle. Across centuries, the same prayers in the same shape have formed saints. The Tradition is the well your grandparents drew from. It still runs clear.
The Orthodox lens
Fr. Georges Florovsky called Tradition "Scripture rightly understood." It is not added to Scripture; it is the air in which Scripture was breathed out and received. The Tradition is what the Spirit has been doing in the Church since Pentecost.
A pastoral word
Start small. Don't try to keep every fast in your first week. Find a parish, talk to a priest, ask one question at a time. The Tradition is meant to feed you, not crush you. "My yoke is easy and my burden is light" (Matt. 11:30) — and the Tradition is how that yoke gets fitted to your shoulders.