A certain sportswear motto says "Just do it", my old trainer put it succinctly using the oft used old saying, if i say jump, don't ask why just how high
As with any exercise, to do it in good form takes practice, the speedball can take longer than others as the hand eye coordination aspect is paramount.
But there is such a buzz when you can get that rata tat tat rhythmn going, so don't give up.
One of your main reasons for following the boxing regime is weight loss, your heart rate does not have to be maxed out all the session to do it, and look at the fact all exercise is calorie burning.
In your intro thread you say you have muscle soreness next day after training, so sounds like you are working hard.
You sound like you trust your trainer, he has planned a regime, follow it and your goals will be reached.