Actress Renee Zellweger is so addicted to exercise, she has wreaked havoc on her body with strenuous physical activity. The svelte star - who famously gained two stone (12.7 kilograms) to play Bridget Jones in the hit British movie franchise - insists she doesn't diet, but keeps in shape by adhering to a strict exercise regime. But the excessive activity has caused permanent damage to her joints. She says, "I ride my bike to the ocean, I dive in and then I ride my bike home. I also run between three and five miles, six days a week. "In fact, I run until it hurts. I have knee and back injuries which mean I can't do any more than that. Oh, and I do yoga, too."