Inclusion Criteria:

• Screening procedures will be performed as part of this study. In order to be eligible to participate in this study, an individual must meet all of the following criteria:
• * Male or female, aged 18 to 80 years
• * Previous infection with SARS-CoV2 at least 4 weeks prior to enrollment, confirmed by laboratory or a healthcare provider. Participants with a documented positive home antigen test will need confirmation of positive COVID-19 antibodies (positive anti-Nucleocapsid antibody test, OR positive anti-Spike antibody test if unvaccinated at the time of the antibody test) to be considered.
• * Presence of physical limitations or significant fatigue since COVID-19 as demonstrated by:
• * Total score \<= 19 on the PROMIS short form for physical function or total score \>= 9 on the PROMIS short form for fatigue, AND
• * Score \>= 1 on the Patient Global Rating of Flu Severity and Patient Global Assessment of Interference with Daily Activities
• * Absence of post-exertional malaise (PEM) as identified on the DSQ-PEM where:
• * Items 1 to 5 has no score \>= 2 for frequency and no score \>= 2 for severity, occurring in the same row, AND
• * Item 7 or 8 is No , AND
• * Item 9 is \<= 13 hours
• * Able to read, speak and understand English or Spanish
• * Able to understand and willing to sign a written informed consent document
• * Willing and able to complete study procedures

Exclusion Criteria:

• An individual who meets any of the following criteria will be excluded from participation in this study:
• * Above normal performance (i.e, \>=100% predicted) in the 6MWT based on normative data for gender and age
• * History or cardiac condition as determined by NIH cardiology to be unsafe for exercise participation (e.g. ischemic heart disease, right- or left-sided heart failure, cor pulmonale or pulmonary hypertension, dilated or hypertrophic cardiomyopathy or non-idiopathic cardiomyopathy)
• * Significant hepatic or renal dysfunction
• * Cancer diagnosis with evidence of metastasis or a life expectancy of less than one year
• * History of stroke resulting in impairments in functional mobility that limits safe participation
• * Active substance abuse including EtOH
• * Severe psychiatric disease, not responsive to treatment or medication
• * History of diabetes and on insulin pump therapy, or uncontrolled diabetes with HbA1c \> 9.0%
• * Pregnancy
• * Acceptance onto a lung transplant waiting list
• * Extreme obesity with BMI \> 40 kg/m2
• * On medications that would influence exercise performance such as beta blockers or antiretroviral therapy
• * Ongoing tobacco and/or nicotine product use
• * Enrolled in another interventional clinical research trial
• * Any other medical or health condition(s) that unduly increases the risk of exercise testing or training, affects the normal physiologic response to exercise testing or training, and/or would otherwise interfere with the ability to interpret the data as determined by the PI