Same as running up stairs, but you don't need stairs.
Do a quick FARTLEK BOOST for your heart and lungs...
Sprint like crazy for a minute, on the spot, a few times a day. It's so quick you don't have time to get hot, but your heart-beats are huge. Being out of breath from time to time is essential for good health.
FARTLEK is the old interval training trick that athletes have used for years. It's not new but it sure works.
Btw, kids love FARTLEK too because it's quick and funny.