The fitness instructor, 69, ran online home exercises during the lockdown.
The Duke of Cambridge has urged Mr Motivator to “keep what you’re doing going” – but turned down the offer of one of his trademark lycra outfits.
William’s words of praise came as he made the TV workout coach an MBE for his services to health and fitness.
Mr Motivator, who was listed under his real name Derrick Evans at the Windsor Castle investiture ceremony, said: “I do this because I love what I do, and it’s been like that since 1993 when my television (break) came along.
“So fitness is a way of life for me, more so than ever now because I think there is a real need not just for the physical side of fitness but also the mental side.”
The fitness instructor, 69, ran online home exercises during the lockdown and hosted a week-long workout with actress Linda Lusardi to raise money for Age UK’s Emergency Coronavirus Appeal.
Mr Motivator, who was previously a staple of breakfast television leading workouts on GMTV returned to television screens amid the pandemic on BBC One programme HealthCheck UK Live.
The trainer, who wore a multi-coloured jacket and matching hat to the ceremony, said about his chat with the duke: “You know what he was so great.
“He was just brilliant.
“He said to me, ‘Listen, I’ve always admired you, I love what you’re doing.
“Keep what you’re doing going’.
“I said to him there’s such a strong relationship between what you have been doing in terms of the mental side and the physical.
“He said ‘Will I have to get into a unitard? I said ‘no, no, no but I have got one made up for you’.
“He said ‘no you look better than me’.”