the 'trick' is to make it a habit, and to do that you have to find a form of exercise that you enjoy. it can't be all 'work.'
when i first began displaying signs of kidney failure, i managed to get pretty sick. i was so stubborn that i wouldn't go to the doctor, and after i did go to the doctor, i resisted going to the hospital until i didn't have a choice in the matter.
the doctors were surprised when i didn't die, actually. i was told that the only thing that saved me was the fact that my heart and lungs are strong. i can only attribute that to 30 some-odd years of tai chi and qigong. even when i was bed-ridden and unable to stand, i found myself modifying some of the old qigong execises to help my breathing and state of mind. this is an excellent site for some of these kinds of exercises...
http://www.herbalshop.com/Xiang/xiang-gong.htmand here is my site, for anyone that may be interested in exploring a system of exercise that's been around for close to a thousand years, now...
http://yinchuandao.bravehost.com/as the old chinese saying goes 'a used hinge will not rust.'
love
~LL~