Mike Coupe, who announced his plan to step down as chief executive of the grocer last week, said his exit was planned and completely his "own decision"
Mr Coupe's exit comes amid a testing period for the retailer, which sought to merge with Walmart-owned Asda in a bid to withstand growing competition from German discount rivals Aldi and Lidl.
The multibillion-pound merger was halted by the Competition and Market Authority (CMA) in April 2019 after it warned the deal could lead to higher prices for customers.
Asked on BBC Radio 4's Today Programme whether he had paid the price for the failed merger, Mr Coupe said: "No. It was absolutely my choice.
"If you looked at our Annual General Meeting last year, 99.5% of our shareholders voted for me to carry on what I'm doing. It's absolutely my choice.
"It's something I've promised myself throughout my career, that at the age of 60 I will stop and do something different with my life."
Mr Coupe said he is approaching his 60th birthday and is planning to "take some time off and spend time with my family".
He will leave the business in May after six years as chief and 15 years at the retailer, with Simon Roberts taking the helm at the UK's second largest supermarket.
Mr Coupe was also asked whether he believed the competition watchdog has now made another large merger in the supermarket sector "impossible".
He said: "I think it is difficult at the moment, but ultimately, I have a very strong view that the industry will consolidate.
"You see the amount of change that is going on in the world of retail, who knows what will happen in the next five to 10 years, but one way or another there will be a significant rationalisation of brands you have taken for granted for a generation."
The comments came as the supermarket pledged £1 billion towards making its operations "net zero" carbon emissions by 2040 - a decade earlier than the UK's legal goal.