using a coin as a 7-sided die

This method doesn't result in evenly distributed probabilities, but I've found it useful all the same. I want to have a random rest-and-fasting day every week, so how can I randomly select one day out of seven to be that special day? An idea came to me: I can use a regular old coin! The coin-toss method works this way:

1. Let heads = Sunday through Wednesday (4-day range).
2. Let tails = Wednesday through Saturday (4-day range).
3. First toss (or 2 out of 3) determines which half of the week will contain the special day.
4. Second toss: let heads = first two days; let tails = second two days.
5. Third toss: let heads = the 1st of the 2 remaining days; let tails = the 2nd.

Et voilà!

How this works in a practical sense:

1. I flip the coin; it comes up heads, so I know my special day will be S, M, T, or W.
2. I flip the coin again; it comes up tails, so now I know my special day will be T or W.
3. I flip the coin a third time; it's heads, so I know my special day will be T.

And there we go. On the designated day, I'll take a break from working out, but I'll also fast.

Of course, by doubling up on Wednesday, I increase the chance that Wednesday will be my "random" day (i.e., Wednesday will always make it past the first coin toss). If you can think of a better way to select randomly from among seven days with equal probability, let me know in the comments, and I might even adopt your method.