You need to be PATIENT A lot of people come to the gym, crossfit box etc and they want immediate results and think that they will get the body of their dreams in a couple of weeks/month. They just don't understand that everything that's worth having in life TAKES TIME. Wether is in business, relationships, fitness... Everyone can build a house in a day, but how long will this house last on the long run...!? It's the same to build a body it's better to take your time and to go slowly but surely and to build something that will last. You also need to be CONSISTENT, PERSISTENT, and of course never give up.
So first of all I don't particularly enjoy endurance training... It actually piss me off..! Endurance is any cardio activity with a steady rhythm from 30 min to more than an hour. I don't do much of it I should do more endurance training even if I don't like it! I really enjoy explosive cardio training but I get bored doing long runs for example. I'd rather do some super intense interval training or sprints. - is it necessary to get better at endurance training ?
It depends on your goals! If I am trying to build mass, because I'm ectomorph, it won't help me at all to do some endurance training because it will highly compromise muscle gains. But if I'm Getting ready for a Muay Thai for example yes I will work on my endurance and run or bike or do anything to improve my cardio!