I find that for me I have to be pushing myself--not killing myself, but challenging myself to get the lung benefits.
I have played around with heart rate training which is very beneficial irregardless of where your current fitness level is. You can read about it on my blog <a target=_blank class=ftalternatingbarlinklarge href="http://cftoo.blogspot.com/
">http://cftoo.blogspot.com/
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My current regimen is MWF elliptical 5K or jog 2 miles followed by 20 min weights and then T I spin which I hate but find challenging so I am trying to stick with it and then TH I have a variety class of strength training/kickboxing/bosu/step/pilates in varying orders. Depending on whehter sometimes I take time to go do a long wokrout on saturday during DD's nap--others its for chores or extra breathing treatmetns or naps. This is not to say I make it to the gym 5-6 days a week but I try. It REALLY makes a difference.
They say any new habit takes at least 50 days to keep so I would set a 3 month goal and see what you can do in that time. I only was able to finally stick with it when I sucked it up and started goign in the mroning before any excuses cropped up. I do my treatments then go and I think I get better airway clearance <u>throughout the day </u>when I do this.