Okay.
Warmups aside, you need dedicated strength and conditioning classes anyways. On top of that, you need to be doing roadwork outside of the gym. That's the reality.
My MMA used to be BJJ for 5 days a week, K1 for 3 days a week, and MMA Fit Conditioning once a week. For Boxing, I'm doing roadwork everyday outside of the gym apart from Sunday where I walk.
In amateurs, having the best gas tank is what can honestly earn you the win because at such little experience, (sub-year or similar) - conditioning will play a bigger part than technique.
If you don't have the cardio, you can't have the endurance to be on the balls of your feet so you'll be flat footed. Your legs will give in without your lower body strength and conditioning so you can throw your punches with form. Your shoulders will strain without conditioning and endurance and you'll lose your technique. You can't be able to hit hard with technique for short bursts without sprints or pylometrics to mimic intensity of fight rounds.
You need the cardio to efficiently learn techniques. That's why gyms emphasis on it. But yeah, it sucks and sparring is way more fun.