Inclusion Criteria:  Citizen of T.C. 18 years old and over Diagnosed with heart failure at least 6 months ago, according to the heart failure classification of the New York Heart Association (NYHA) II. or III. in phase Left ventricular ejection fraction < 50% Volunteer to participate in the research Piper fatigue scale score of 4 and above Hb value of 8 gm/dL or more Having an Internet connection and a smartphone at or near Patients meeting all of the above criteria are included in the study.  Exclusion Criteria:  Those who are taking or doing yoga/pranayama/deep breathing exercises before diagnosis Having a problem (due to deviation of the septum, etc.) that causes difficulty in doing breathing exercises Have a serious mental illness/cognitive problem that may affect their perception or communication Receiving chemotherapy treatment Have had cardiovascular surgery in the last 3 months Those who have had myocardial infarction in the last 3 months Have had valve surgery in the last 6 months Have chronic obstructive pulmonary disease or asthma Chronic renal failure with glomerular filtration rate < 30 ml/min Have a serious disease related to heart valves Piper fatigue scale score below 4 Hb value below 8 gm/dL existing Cardiac Resynchronization Therapy (CRT) Those who were informed about the research but did not want to participate in the research  In case of any of the above criteria, the patient is excluded.