LONDON—Lewis Hamilton says his drive for social justice, and campaigning for diversity, has given his life a real purpose while also helping prolong his record-breaking Formula One career. The 36-year-old Mercedes driver, winner of a record 100 grand prix, is chasing an unprecedented eighth world championship in a tight battle with Red Bull rival Max Verstappen, 24. Dutchman Verstappen is 12 points clear with five races remaining. Hamilton told Sky Sports television that his campaign, and use of his platform to push the conversation, had given him fresh energy and made him mentally stronger than ever. “This year I’ve not been drawing on past experiences, I’ve been drawing on feeding off this energy of doing this positive work,” he said. “So now it’s the work that I’m doing in the background and then I’m turning up and I’m enjoying this job. “Is it helping me race? I think so, yeah. …