Did some more HIIT after lifting weights last night. I honestly can't believe how much easier it's getting. I don't feel like I'm suffocating from lack of oxygen anymore. I feel really motivated to get as fit as possible cardio wise. Not just for tennis, but overall health as well. If I could get my resting heart rate into the 40's that would be awesome.
I'm going to make it standard protocol after lifting weights so I don't slack off and forget about it after a while which is what I usually do with cardio. That'll make it at least 2x/week and hopefully once or twice more depending on how the week goes. I usually get 2 matches in a week which can be hit or miss on the cardio aspect.