Husband wants to start his own Business

Last night my husband and I were talking and he was saying that since I'm going to get my realtors license soon that in the next few years he wants to slowly make our own business of flipping houses. Where we work on them and redo things and make update and I resale them but I still have a nervous feeling of its a good idea. My husband is currently in college full time at a local University here to finish obtaining his Bachelors in Civil Engineering. So he has the brain for it and for creating our own business and he's amazing with finances and calculations so why do I still feel a little nervous. Is it the excitement or just nerves of doing something new and different?