Mr Morgan, 96, has done 100 times around Ropetackle where he lives, and has so far raised just over £2,900 to help the homeless.
Inspired by Captain Sir Thomas Moore, Mr Morgan followed a circular route around Ropetackle and Broad Reach, and he encouraged anyone who spotted him to give him a wave.
He said: “I have completed my walk and the fundraising is still active, with just a last few pounds to reach £3,000 for the homeless, which would be wonderful.”
Mr Morgan was a corporal in the 48th Mobile Battalion of the Warwickshire Home Guard during the Second World War. He became a lieutenant in 1949 and then a captain in the Royal Army Medical Corps in 1950, later carrying the same rank in the TA.
Mr Morgan became a doctor on the East Lincolnshire coast between 1954 and 1968, worked in Norwich from 1968 to 1985 and was then a locum in the parish of Hellesdon until he retired.
His son Jonathan, who lives in Hove, followed in his footsteps and was a GP at Shoreham Health Centre in Pond Road.
Mr Morgan said: “I live in a beautiful flat in Ropetackle. Until I eventually retired aged 78, I had spent my life as a GP.
“Inspired by Captain Tom, I am walking 100 times around my block of flats during May for Crisis, which helps the homeless, because I have always had a beautiful home and they have not.
“It’s a fair way and the most times I can manage is five in one day.”
Visit www.justgiving.com/fundraising/John-Morgan35 to make a donation.