This is a little console program I wrote that simply loops counting down a list of timeframes (in seconds).
Aka htimer 10 60 → countdown 10 .. 0 (from 10 to 0) seconds, then countdown 60 .. 0 then 10 .. 0 again.
It accepts any number of timeframes as input.
htimer 10 5 60 80 → 10 .. 0 >> (then) 5 .. 0 >> 60 .. 0 >> 80 .. 0 and repeat (indefinetly).
It displays intermediate steps in a sane way. Aka ∞ .. 10 it prints the remaining time every n mod 10 = 0 step >> 5 .. 1 every second, 0 is not printed, instead it says "NEXT".