become fatigued, stop
劵 centers on exhaustion that forces a stop: becoming so fatigued that one must cease activity.
劵 combines 龹 (possibly related to rolling or wrapping) with 力 (strength), suggesting strength being rolled up or exhausted, leading to fatigue and stopping.
The top 龹 looks like something rolled up, and the bottom 力 is strength. Imagine your strength being rolled up and put away, leaving you too fatigued to continue.
For ケン, picture a tired person named Ken who has become so fatigued he must stop: Ken -> ケン, and his strength is all rolled up.