Callum Wheeler, 22, has been handed a life sentence with a minimum term of 37 years at Canterbury Crown Court for the murder of 53-year-old.
He waited for the mother-of-two in Ackholt Wood while armed with a large metal bar before ambushing her near her home in Snowdown, Kent, on the afternoon of April 27 last year.
Prosecutor Alison Morgan QC said Mrs James was subjected to a “brutal and fatal attack” when she was off duty.
She added: “This was a murder involving sexual conduct.”
Wheeler was seen armed with a weapon while roaming around the countryside the day before he killed Mrs James who was off duty.
He was carried into the Canterbury Crown Court dock on Friday, wearing handcuffs, by staff from Broadmoor high security psychiatric hospital, in Berkshire, where he has been held.
Sentencing him, Mr Justice Wall told him: “The attack you launched on her was brutal and vicious.”
He went on: “Your actions have not just served to end the one life prematurely but have also destroyed the lives of the whole of her family.
“I am drawn on the evidence to the obvious conclusion that this was a not a spur of the moment aberration by you. Rather it was an attack which was planned and thought through in advance.”
He added: “You were there looking for a lone female victim and you were sexually motivated to do so.”
Wheeler was found guilty of murder in May.
Mrs James’ husband Paul James, daughter Bethan Coles and son Patrick Davis read their emotional victim impact statements in court.
Her children said their mother’s murder had given them a “life sentence”.
“To lose my own parent, the woman I loved the most in the world is truly awful,” Ms Coles said. “To know how she was brutally attacked in broad daylight having run for her life is horrific.
“It haunts me every day of my life.”
Mr Davis said his mother’s life had been taken because of a “twisted individual’s strange desires”.
He said: “He should never see the light of day again. Why should he? My mum only wanted to walk her dog but had her life ended by that disgusting creature.”
Mrs James’ husband repeatedly broke down in tears as he told how “my life was finally complete when I married my soulmate”.
“My hopes and dreams were taken,” he said when his wife was murdered. “I actually felt I died too.”