Why would having no freedom be challenging to a slave?

It would be challenging because being a slave does not allow anyone to do anything they would like to do or have any freedom

There are an endless amount of answers towards this but summed up some of the answers would be the risk of having a family due to you could be sold around and loose everything you know and love all at once another reason is the fact that they could not take brakes to enjoy there own time they had to work every day and the last reason is because the lot of them were mistreated not all were and some stated that they were treated better as a slave then when they were freed but that is a very rare case