This person always goes the extra mile. This isn’t necessarily a bad thing, but it can lead to unreasonable expectations from higher-ups. You want to tell them to dial it down, but you also don’t want to come off as bullying the hardest worker.
Keep this colleague busy with loads of tasks, no matter how small. Career development coach Dianna Reed says such workaholic tendencies stem from a want to feel needed. So if you enrol their help in things, a) you’re free to focus on the important stuff at work and b) you boost the confidence of the Market Spoiler.