@lilianna
Shortness of breath has long been an issue, but I nebulize levalbuterol and/or inhale Symbicort to improve my ability to get the heart rate up.

When I can't get out, I use a treadmill (can set incline & speed) or bicycle (can set resistance) - I go hard & fast to get the heart rate up. Sometimes I have to stop to catch my breath. But even raking, sweeping or mopping can get my heart rate up sometimes.

I find home activities that require position changes help move mucus - like bending and reaching in the garden, or even putting the clothes basket on the floor, grabbing an item and folding it, walking quickly to the drawer and putting away, then repeating - as quickly as possible -can increase heart rate. Emptying the dishwasher one piece at a time and walking/reaching to put things away is another option. Weeding in the garden can be done aerobically too. Yesterday, in two hours, I did 6000 steps putting away lawn art and pulling dying plants and putting them in compost... And it takes 8000-9000 steps over 90 minutes for me or my husband to mow our yard (with water/breath-catching breaks.)
Everything counts! Today we parked several blocks from the doctor's office and walked to and from the appointment.