Or maybe, despite life-threatening cystic fibrosis and talk of his 40-year life expectancy, he's got his mother's buoyant attitude. The teen quietly rotates his large Styrofoam cup of sweet tea to reveal smiley faces he's been carving around the rim. The Springfield mother-son duo return from doctors' visits at a Jacksonville pediatric clinic with good news and inside jokes. Dena types the good news on Facebook, for example: "height up, weight 97 lbs, lung functions great." Jokes, forged in extended waits, or a 20-day hospital stay at Nemours Children's Specialty Care, still deliver. Asthma, they thought, prompted breathing treatments, and he did have a lot of sinus infections. Bruen, who just finished eating 11 chicken nuggets, pulls out a white large bottle of enzymes called Zenpep. With cystic fibrosis, the teen fights to gain weight, urged to take in 3,000 calories daily. Forget healthy eating as most count vegetable-rich diets; doctors want Bruen eating high fat and high protein. The enzymes — he swallows up to 28 of those pills daily — help his body absorb protein and fat. He earns $10 gift cards to Wal-Mart from the Jacksonville clinic when he gains enough weight. [...] Dena may have perfected her Twinkie milkshake with sweetened condensed milk, Twinkies, of course, and Boost. Cystic fibrosis affects a person's respiratory or digestive system, or both. Coughing, bacteria and scar tissue add challenges.