I've been a working student for a few different trainers (mostly my mom's trainer friends lol). I loved the time spent with horses and getting to ride. I didn't even mind the really difficult stuff, either.
While most everyone I worked for was totally great and really appreciative of me, one lady, not at all a friend, was a total nightmare to "work" for. My only advice is that, if you find yourself in a bad situation, don't be afraid to get out.
Yes I worked all summer, it was very tiring but I love horse riding and also show jumping and I need much money