We had a politician do this a few years ago, while running for Governor. He was former state senator Thomas Birmingham.
Birmingham had been a heavy smoker all of his adult life. He was told by his doctor that he really should quit, and try to lose some weight. He quit cold turkey, and took up cycling from his home in Chelsea, to the State house. This was only a few miles, but as time went on, it got easier.
He decided to bike around certain areas of the state, because the bike made it easy to meet and talk with people. He promised that if elected, he would make cyclists' rights, and construction of the proposed Mass Central Rail Trail, a priority.
Alas, he did not get the democratic party nomination, and thus, did not become Governor. Dang! (The Dems chose Shannon O'Brien as their nominee. No further comment required. But, "The best bad guys always return".)
I also wish we had more politicians like these people. We do have a few, in local and national offices, but not enough.