Boxing is awesome cardio!!! I don't think people realize until they try!!! Same for jump rope. Looks easy....then you try and realize ten seconds in that it's extremely demanding and will wind the average person within ten seconds!!!

My cardio is done on elliptical machine. Low impact, can set resistance and get a lot out of 40 minutes.

Maybe you can switch the order of things, to help with weight lifting? Start with what you usually finish with. Or, use dumbbells instead of barbells or vice versa. I'm using a lot of dumbbells now in place of barbells. Really requires a LOT of those balancing muscles and muscle symmetry. I use almost no machines. Almost all free weights. So much better. My least favorite machine; Smith Machine. I see people squat on that machine all the time. They are missing out on so much.

P.S. That's an excellent resting heart rate. I'm around 55 to 60 and that's considered really good. I do drink about six cups of coffee a day though lol.