What are limitations for someone with Chronic Bronchitis?

We are an active family who likes to hike. My husband is currently seeing a doctor who is telling him that he has Chronic Bronchitis (he's never smoked a day in his life). He's had severe pneumonia two times in the past 7 years. My husband is telling me that the doctor has told him that his hiking days are through - that the exertion will be to hard on him. Is this true? We don't do intense hikes - but the last time we did hike he had a hard time going uphill. He doesn't exercise regularly - hiking is our exercise and he is overweight.