What kind of fast? My only advice would be to do this under strict medical and spiritual guidance.

Medical for obvious reasons and spiritual because fasting can easily invert from being a significant positive to a significant negative without the support and guidance of a spiritual elder or counselor.

As with a prayer rule it's probably best to start off small and build up over time but maybe you have done this.

What do you mean by fasting?

If you mean, abstaining from certain foods - then yes. The fasting rule of the Orthodox Church on general fast days is no animal products (meat, eggs, dairy), no alcohol, and no olive oil. Or put another way, eat simply, avoid rich foods, and do not eat to fullness.

The Church does prescribe strict or "black" fasts on certain days of the year - for example, on the first three days of Lent, Good Friday, the eve of Nativity, and the beheading of St John the Forerunner.

If you mean abstaining from all food altogether - then no, and I don't recommend it. Fasting like anything else is a discipline, both spiritual and physical. Taking something like that on should be done with humility and under the guidance of a spiritual father. In general, extraordinary or extreme acts of asceticism should be taken with caution, because they offer temptations in both success and failure disproportionate to their spiritual benefit.

I am no spiritual father, but I can tell you 100% what mine would say. Keep the typical prayer rule of morning and evening prayers, and follow the fasting rule of the church as you have the strength - for example, abstaining from meat only on fasting days - for one year. If you can do that, glory to God! and move on to higher levels of asceticism.