Hi team, I’m 43 years old. I’ve never had cardio capacity. Been overweight since 19 years old. Ive lost 40 pounds in 1 year. I can see my evolution in weight training but my cardio capacity is terrible. I can’t run for damaged knee but going up 6 stories with stairs kills me, I also ride mountain bike and as soon as the uphill start I struggle severely. My heart rate rises very fast and at 163 bpm I have to stop or I start to get dizzy. Any advice or program on how to improve this. I also swim 2-3 times a week and also walk some times.