Countdown beeps during rest

When resting between sets I often walk away from my phone and sit down. Quite often, I can zone out as well, and I forget to watch the rest timer. When this happens I end up having to rush to get my belt back on and get into position before the next set.

It’d be great to be able to set times for the beeps during a rest set, so that if I’m resting for 60 seconds I get a beep at 20 and 10 seconds, or if I’m resting for 90 seconds I can set one at 30 and one at 10.