Tell us more.

Are you keeping it outdoors or indoors?

If outdoors, what's the weather been like? Around here we had very warm weather for a couple weeks followed my more seasonal 60s/40s. Those cooler temps would probably slow down a tortoise.

If indoors, what temps are you providing, how long are the lights on, etc.

Are all of your tortoises slowing down, or just one?

Any signs of nasal discharge or other respiratory problems?