Keeping turtles can seem like an easy task, but that is very deceiving. One of the biggest turtle hurtles is overfeeding. You can't let your turtle get fat. Their shell doesn't grow as fast as their body. This can cause shell deformation and keep the turtle from being able to tuck it's legs and head.
Box turtles are relatively healthy, but there are viruses then can get, and are known for "shell rot".
They need to be kept VERY clean. Both the turtle and their habitat. Intestinal parasites are also common, especially if they are outside a lot....which I highly suggest doing. Being outside helps with their overall health, and can keep them from vitamin deficiency and bordum.
Believe it or not, bordum can cause mental health issues in turtles...and most other animals.
Finally, they CAN live a very long time. Most captive Boxers live about 25 years, mostly due to owner neglect unfortunately. But I've seen 60+ year old Box turtles in our clinic. They can last generations in a family.
Next to parrots, turtles and tortoises are the most abandoned pet.
They dont need a ton of care, but they need specialized care. Find a good Vet who is experienced with exotics.
Turtles are hilarious if you pay attention. They are smarter than most dogs...and they love to play.