Much as I hate to say it, you'd probably achieve this far more efficiently if you just "sucked it up" (pardon the expression) and just went to more classes. But to be fair, I'm just cynical. Everyone I've met in person who has said "I want to get a bit fitter so I can cope better before I do 'X'" has always ended up not doing 'X' at all and not finding the motivation to try. Like you said, you've only had a few sessions so far. This time a few months on from now you'll probably feel like a different person. Have you thought about getting a hanging bag or a free standing bag for when you're at home? Push ups and pull ups are always sexy. Doing multiple rounds of shadow sparring in your own time at home is also pretty good for your cardio an' such. I'm a fan of doing rope work at home, but that's my personal choice. I think you'd have to check with the other folk who actually know this stuff far better than I do, but I believe the answer is closer to "it depends".