Some of you were complaining that some quests are difficult, to the point of being nearly impossible.
Overall the quests are not supposed to be easy, they are meant to offer a challenge to those interested.
Some of them are easy, some of them are harder, some seem impossible.
If you are required to enter a high level horse in a number of shows, you likely do not have that horse, but you could try to convince the owner of such a horse to give you their horse for a while.
Ultimately you can cancel that daily quest and you will get one the next day... (or you can really try your best to complete it)

PS: The level for entered/created shows has just been capped at 100.