Eligibility Criteria:
Adults aged 65 years or older of any sex, gender and ethnic background who meet the following criteria will be eligible to enroll in the present study:
Inclusion Criteria:
* scheduled for elective TKA within the next week to two months (can be second knee, but cannot be a revision of the original knee)
* self-reported good health, including denial of debilitating illness that may affect participation in or be potentially exacerbated by deep, controlled breathing (i.e., chronic obstructive pulmonary disorder \[COPD\], symptomatic or advanced heart failure, complete heart block, glaucoma, epilepsy)
* denial of conditions that alter cortisol release or that require corticosteroid therapy (i.e., Cushing's syndrome, Addison's disease, pituitary tumors, adrenal gland tumors, asthma)
* denial of severe psychiatric or cognitive conditions that warrant the need for a durable power of attorney (DPOA)
* able to understand written and verbal English.
Exclusion Criteria:
* currently taking oral, injectable, intranasal, topical, or inhaled corticosteroid medications (i.e., prednisone, hydrocortisone, dexamethasone, methylprednisolone, methylprednisolone acetate, triamcinolone, betamethasone, mometasone, fluticasone, budesonide, clobetasol)
* do not have the technology requirements to complete data collection (i.e., participant does not have a smartphone, tablet, laptop, or desktop computer; lack of reliable internet)
The following exclusion criteria may affect participants' ability to remain in the study following enrollment:
• Development of complications during surgery that require prolonged hospitalization into Postoperative Day (POD) 2 (e.g., postoperative intubation and ventilation requirements, intractable pain, intractable nausea/vomiting, signs of infection or sepsis)