lots to do in their enclosure. plants, rocks, hides, things like this... outside walks or outside enclosures help. anything that helps with keeping their stress level low
Read all you can about how to care for them in captivity AND about their natural history. Here's a neat article about them that was recently shared with me. I learned quite a bit. I don't necessarily agree with 100% of it, and there is still much to learn, but its a great read for anyone in to russians. http://www.dght.de/ag_schildkroeten/pdf/ehorsfield.pdf