If you thought the life of a sloth was one of luxury, you’d be wrong. It isn’t all naps, hanging out, and photo-ops.

This video from the Washington Post shows the strain a sloth has to go through each time nature calls. Fortunately for the sloth, this is only a weekly occurrence. And fortunately for their science reporter, Jason Bittel, his visit to the National Aviary in Pittsburgh coincided with this magical moment.

Since they only go once a week, they can lose up to a third of their body weight in one session. As you can imagine, that can’t be too comfortable.

But this isn’t even half the ordeal for these sluggish mammals. In the wild, their trip to the bathroom is one of the few times they ever leave their canopy of trees for ground level. With a top speed of 6 centimeters (2.3 inches) per second, they’re easy pickings for predators.

As the Washington Post reports, there could be a strange reason why sloths might make this journey of relatively epic proportions. A 2014 study from Proceedings of the Royal Society speculated that sloths do their business by their desired tree so that moths lay their eggs on it. These moths then land on the sloths along with lots of algae-friendly nutrients. This helps the algae grow on the sloth, which in turn helps keeps the sloths nice and green and camouflaged from predators.