The Prince of Wales says he stops talking about topics he feels strongly about when he becomes king because he "is not so stupid".
He has been fighting for such issues as the environment for decades, but says he will not do the same thing as a monarch.
In an interview for a BBC documentary commemorating 70th birthday, Prince Charles said the idea of continuing the intervention is "nonsense."
He said he would have to work within "constitutional parameters".
The campaign covered environmental issues, nature conservation, architecture and the use of genetically modified crops.
Totally different & # 39;
In an hourly program, he was asked what some people call "interference," but he said he always tried to remain "non-party political".
He said, "I think it is vital to remember that there is only one state at a time, not two.
"So you can not be the same as a sovereign if you are a prince of Wales or an heir.
"But any idea that I will continue exactly the same way if I have to succeed is completely nonsense, because both situations are completely different."
Asking whether his public campaign will continue, he said, "No, it will not, I'm not that stupid.
"I realize that this is a separate exercise that is sovereign, so of course I fully understand how it should work."
John Bridcut, the documentary filmmaker who watched for 12 months, said Prince Charles had "made a little bit of" use of the word "mixing," rather than thinking of his interventions as "motivating."
The heir of the throne said, "If I worry about inner cities, like I was forty years ago, if it's interference, I'm proud of it."
Nicholas Witchell, royal correspondent
He spent his adult life trying to "change". It has often led the Prince of Wales to talk about topics he feels deeply about: environment, GM crops, inner cities, architecture, education, homeopathic medicine, and more.
Prince Charles was accused of "interfering". Occasionally it caused irritation in government offices that had to respond to his hearty "black spider" of handwritten letters that were still politely but often urged to appear on the prince.
All this raised more concern. Does Prince Charles fully realize that if he succeeds his mother and becomes a British king, must these interventions stop?
Those who know him have been saying for years that he understood that there was a line that could not be crossed as a sovereign.
They say he fully understands in private that he will have to stop a "campaign" like a king.
Prince Charles himself has always said he says so much in public. He felt that any reference to how he would work as a monarch could be regarded as disrespectful to his mother.
However, with the Queen now in his 93rd year, and with Prince Charles to celebrate his 70th birthday, he finally said – publicly and explicitly – that he acknowledges that his interventions in public debate matters will have to stop as soon as he becomes king.
"You operate," says BBC, "within constitutional parameters".
It is reasonable to assume that his assurance will be heard with some relief within Whitehall and the corridors of power.
"He is great"
Mr. Bridcut said: "People who think they are troubled by them and want to be king are very wrong.
"It's not something he can predict because it will inevitably occur after his mother's death."
He added that the Duchess of Cornwall, who is also interviewed in the documentary, "stresses that this burden does not heavily weigh on the shoulders."
The BBC received exclusive access to Prince Charles's film, which will be 70 years old on November 14th.
The Duke of Cambridge also said he wanted his father to spend more time with his grandchildren – Prince George, Princess Charlotte and Prince Louis.
Prince William said, "When he's there, he's great," but "we need him as much as possible there."
"People on His Side"
Roger Harrabin, BBC Environmental Analyst
The Prince has warned of man-made climate change decades ago. Some were controversial at the time, but there is now a scientific consensus on the threat.
In the wild, he predicted a huge loss of species. Campaign against the destruction of the rainforest and will be happy with the recent focus on the impact of agriculture on forests and hence on the climate.
His worries about soil have been tiny for some observers, but now it is acknowledged that many areas face a crisis of degradation and loss of land.
In these matters, the main stream flowed to the future monarch.
For genetically modified crops, the prince remains in conflict with the scientific institute.
On other hobby horses, such as homeopathy and architecture, he expressed his opinion rather than the fact – but he still has a few people on his side.
- Prince, son and heir: Charles At 70, will be screened at BBC One on Thursday 8 November at 21:00.