Enjoyment
Students predominantly come to you to seek greater enjoyment of skiing. Whether they are looking for increased skill and challenge, better competitive results, or a greater appreciation of the mountain environment, enjoyment is key. If the lesson environment is not fun, they are less likely to progress and less likely to return.
What makes skiing fun will be different for different people. For some people just being active is fun, for some being challenged is fun, for others it is the learning and understanding that will be fun. Some students will simply find the social interaction of skiing with other people fun.
Identifying when students are enjoying themselves is important in understanding what motivates them. Smiles and laughter are the most obvious indicators, but be aware that some people may prefer to hide their emotions, so check in with people rather than trying to force them to have fun. As a general rule, if you are having fun then your students will be having a good time as well. So make sure you enjoy the learning process with them too.