Gwen Stefani may be a big softie when it comes to her romance with Blake Shelton, but one thing that's solid as a rock? Her bikini body. The "Used to Love You" singer, who shares kids Kingston, Zuma, and Apollo with ex-husband Gavin Rossdale, was spotted showing off her enviable abs while walking in the sand in Newport Beach, CA, on Sunday. The 47-year-old paired her colorful bikini top and cover-up with jean shorts, a baseball cap, a Vince Camuto tote, and a flannel shirt tied around her waist. Gwen appeared to be on her own for the outing, which makes us want to book a solo trip to the beach ASAP.