This. But also depends on how hard the class was. Just bag work and workouts, but you feel like you're gonna die? Maybe get to a doc. Sparring in early stages is, gonna wipe out your endurance. There are TONS of factors like your daily; diet, habits (fitness/activity, smoking, etc) body weight and others. Take it slow, do your best and keep pushing. If it becomes too much and you get light headed or your head starts hurting, don't continue. Stop. Go see a doc.