Stick with your hobbies, and include your children with it. I don't have any kids, but coming from a guy who grew up in a broken home with two very unhappy parents, I can tell you that maintaining your own happiness for yourself and your fiancé is very important for your children. Your potential unhappiness from giving up your own life and interests will eventually trickle down to your kids. Owning reptiles can be a very enriching activity for both parent and child to bond over, learn responsibility, and maturity. Interacting and caring for animals as a child also widely expands the child's knowledge base, curiosity and understanding of the world around them.
Taking a fishing or hunting trip once in a while to clear your head and refresh yourself is going to pay big dividends over time. Don't give it up, instead include your kids in the activities and help pass down your knowledge and understanding to future generations.
Granted I don't have kids currently, but my beautiful fiancé and I are considering them in the future, and hope to maintain our love for nature, hiking, camping etc even with children.