@1nan - Believe it or not I have no pain so far with multifocal adenocarcinoma of the lungs. My pain is more emotional so being able to write and mentor for Connect helps me immensely. I also write a blog. Relieving stress is a benefit because stress is a big cause of loss of energy and stamina. I also need to increase my stamina and you are right, lifting weights are not enough, but are necessary for stronger muscles and bones. To increase stamina at home would need a more intense exercises. Increase speed, eliminate times in between sets. I walk up and down the steps in my house more often and I'm about to start riding my bike again now that the humidity is gone, or almost gone. Walking, biking, swimming or anything that will make your heart beat faster.
If you're out of shape and need a quick way to increase your stamina, make these five exercises part of your regular fitness schedule.

Stair climbing. Stair climbing can really help with your stamina. ...
High-intensity interval training. HIIT workouts are really tough. ...
Lifting. ...
Cycling. ...
Swimming.
Of course anyone who wants to do these and has limitations should make sure that they can do these without injuring themselves. There are tons of videos on you tube and a doctor's ok would be good, or a trainer.
Everything needs to be eased into, don't you agree? Does anyone have other suggestions?