Father of twin daughters here. Be ready for the most amazing and rewarding adventure you will have in life. The first 3 years will be tough, but as others said, getting them on a routine is critical to you and your wife getting rest. My daughters are now 23, both graduated college and love the outdoors. My wife and I took them on hunts, fishing, camping, ski, climbing trips starting when they were 1. Now both of them are into backpacking, climbing 14ers, skiing, snowshowing, running and archery. So dont hesitate to live an active lifestyle with them early on, theyll pick it up with you.
Congrats!
PS: dont forget to take care of your wife...the first few years will be particularly draining for her.