Not a legalistic exercise but a spiritual discipline

In the midst of a lengthy post concerning the Byzantine Lenten fast, John, at Ad Orientem, offers these sage words which we do well to heed:

[F]asting is not a legalistic exercise. God does not particularly care how
strictly you are able to observe a 5th century dietary code. Eating a
Cheeseburger during Lent on a Friday is not a mortal sin (except possibly to
your waistline). If you do eat one and happen to die before going to confession
you do not need to plan on being buried in an asbestos suit. Point in fact very
few Orthodox laymen keep the fast in its full rigor. I certainly have yet to
keep the fast with anything close to perfection.

That said one should not just blow it off. Fasting is a spiritual
discipline intended to stretch the body and help tame the passions. And it is a
very important weapon in the spiritual warfare that we are engaged in more or
less continuously until we die. So when you fall, don't give up. Pick yourself
up, dust yourself off and get back on the wagon.

Also it serves no purpose to abstain from all manner of food and drink if
we do not also give up our vices. In particular be wary of gossip.
Your fast is your own business and no one else's (save God's and your
confessor's). Likewise how others are keeping their fast is not your
concern.