For those keeping the full Yom Kippur fast this year, it will begin on Sunday 20 September at 18:49 and end on Monday 21 September at 19:48.
Of course, Jewish tradition is clear that we should not fast where doing so may harm our health. Yom Kippur is not a test of endurance, nor is its meaning measured to the minute. All of us are encouraged to reflect on teshuva (the concept of repentance, return and new beginnings) in our own way.
If you are unable to fast, you may find this prayer and meditation helpful. You can find out more about the festival and its traditions here.