Depends, what exactly are you doing cardio for? Are you talking 90 min for the week, day? What type of cardio, if you mean walking on the treadmill, honestly, that don't do shit IMO.
Running mom, I disagree. I damaged my arm years ago and after the operation I couldn't lift weights for almost 2 months. Running was to jarring and painful for my arm. I was on the track team in high school and college. I know what hard running is.
I started walking at 3.8 MPH on a treadmill. My method was walk a level grade for a quarter mile. Every quarter mile or 400 meters I would raise the incline 1%. So the first lap was zero incline and the second was 1%. The third was at a 2% incline and so on. I would go as high as I could to exhaustion then reward myself with a 0% last lap incline. I did this for about 4 weeks. When I went for my first run I flew like wind. Walking fast on a treadmill is very hard work especially on an incline. Even now from time to time I do a walking work out and it kicks ass.