Each participant will be randomly assigned to one of the two groups: a) the walking program with a high-intensity Inspiratory Muscle Training (IMT) program, OR a walking program with a sham IMT program. The Sham group will be trained at a low intensity. The training threshold for the Experimental IMT group will be set at 60% of PImax which will be adjusted during weekly follow up. The frequency of training: 5x/week (1x/day preferred) for 6 Interval Levels at each session (6 inspiratory efforts in each level): (1) 60s rest interval; (2) 45s rest interval; (3) 30s rest interval; (4) 15s rest interval; (5)10s rest interval; (6) 5s rest interval, trained to exhaustion. The sham IMT intensity will be set at fixed 15% PImax. Research participants will be blinded to the group assigned. The time commitment for their IMT training is about 15-20 minutes per training session at home. Weekly follow up on their maximal inspiratory pressure (PIMax) will be done at the School of Physical Therapy in Dallas, then they will train at the new IMT training intensity with a breathing device for 15-20 minutes. Researchers will also make a copy of their weekly step counts log. Each participant will be given a breathing device for the breathing exercise.