Complex sentence: Piana won the Mr. Teen California at age eighteen, and in 1998 he was named Mr. California, but quit bodybuilding competitions in his final years as he preferred to spend his time as an Internet personality and to promote his business, 5% Nutrition.
Split into simpler sentences: Piana won the Mr. Teen California at age eighteen, and in 1998 he was named Mr. California. However, Piana quit bodybuilding competitions in his final years as he preferred to spend his time as an Internet personality and to promote his business, 5% Nutrition.