I recommend starting out by training 3 to 5 days each week, with a day of rest somewhere in the middle. Your body needs rest days to recuperate and get stronger. On your rest days, you can still find other options to be active if you choose. Consider cross training by taking a long walk or bike ride. Running, swimming, hiking, or any other exercise that gets your heart rate up are also good to improve your fitness and can be safely be performed on rest days.