To some of us, Olivia Newton-John will forever be Sandy, the preppy teen who transforms into a spandex-clad bombshell in the 1978 musical rom-com Grease. While that role may have catapulted her into the spotlight, Newton-John was already an established singer-songwriter making unexpected waves in the country music industry. Born in Cambridge, England and raised in Melbourne, Australia, Newton-John recorded her first single at the age of 18 and earned a Grammy with the 1973 album Let Me Be There. Oddly mirroring Sandy’s reinvention in Grease, Newton-John adopted a rockier style for 1978’s Totally Hot, slipped on roller skates for the deliciously cheesy, ELO-soundtracked fantasy Xanadu (1980) and then topped the charts with “Physical,” a sultry aerobics anthem Billboard once ranked as “The Sexiest Song of All Time.” A breast cancer survivor who’s dedicated to “educating and encouraging women to take a positive role in their breast health,” Newton-John is also a philanthropist and humanitarian who works closely with the Amazon Center for Environmental Education and Research, and launched National Tree Day, an initiative that’s added 10 million trees to Australia since its inception in 1992. Although her recent releases lean toward adult contemporary, holiday fare and even new age, Newton-John treats concertgoers to gems from her decades-spanning, genre-hopping career, interspersed with endearing anecdotes. Still stunning at 68, the Aussie icon takes a break from her extended “Summer Nights” residency in Las Vegas for a quick November tour stopping at the Majestic on Sunday.