Oh, this is a tricky one. Here's my quick thoughts:

1. No one knows what's best for you more than you do. If you love what you do and you feel good about the level of energy you're committing to your work, then great.
2. That said, I definitely recommend you check in on all parts of your life as a way to keep yourself honest. Diving deep into your career can be very rewarding, but it can become a slippery slope if other parts of your life (like friendships and physical health) start to get deprioritized.

And if this commentary is mostly from colleagues, the best case here is that they're just genuinely looking out for you. Worst case is that they may feel like they're having a hard time "keeping up" with you. Either way, you have to do what feels best for your life and your personal ambitions and just be kind to everyone along the way.

Good luck!

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and p.s. Thanks for being a teacher... it's one of the most important jobs in the world.