Kostas Mitsaris was born in Athens in 1964 and has two children, Kelly and George. In 1981 he graduated from the Athens 6th Senior High School and in 1987 from the Athens Sports Academy with a major in basketball.
In 1985, while he was still studying, Kostas set up the women’s section of the then newly-opened Gold’s Gym in Ilioupoli, where he worked as a fitness trainer until 1988. In 1992 he obtained a certified personal trainer and sport and fitness nutritionist diploma from the College of Marlboro in New Jersey, USA.
Upon his return to Athens, Greece, he resumed his personal training sessions with clients and, at the same time, served as the representative of the sports supplement and nutrition product company Vitalife for a period of three years.
In 1995 he obtained a lifeguard diploma and, meanwhile, opened the Extreme Sports Centre and, of course, continued to provide personal training sessions.
In 1997 Kostas completed a first aid and cardio-respiratory resuscitation seminar at the Evangelismos hospital in Athens.
In 1999 he obtained a diploma in canoe and kayak training as well as a rafting guide permit.
Between 1998 and 2002 he worked as an independent personal trainer at the Joe Weider gym in Alimos then at the gym Overall in Alimos from 2002 to 2004, as well as at Gym Tonic in Glyfada occasionally.
Between 2000 and 2003 he participated in seminars on post-surgery and post-injury sports rehabilitation and muscle strengthening for athletes in the cities of Nice, Budapest and Madrid.
Kostas has written articles on fitness and nutrition for the English-language Athens-based newspaper Athens News and the Greek magazine Fit for Fun.
Since 2012 Kostas Mitsaris works together with his son George Mitsaris who is a certified personal trainer by ISSA International sports sciences association USA.
From 2013 to 2015 worked as personal trainer for two seasons in the known resort of Gstaad in the Swiss Alps.
In the summer of 2015 he was invited to the 100.3 Zoi.gr radio broadcast with Christina Vidou talking about fitness, nutrition and life coaching, continuing until today, for the year 2016 he wrote about the site of the southern suburbs nou pou.gr and from the beginning of 2017 he writes about the big news site skai.gr as well as other big sites
2017 began with personal training in Monaco and in nearby cities on the French Riviera, alongside his clients in Greece, who coached with his son and partner Giorgos Mitsaris.
In 2018 he began to write his first book “The Well-Being Bible” which will be released in early 2019.