To be healthy and fit in winters you need to do the following things-
# Usually in winter our water intake decreases but it is very necessary to provide body with the required amount of water.Drink at least 7-8 glasses of water which will help you in being hydrated.You can also take fluids in the form of vegetable soups,green tea,vegetable shorba will not only help in providing your body enough water but also helps in maintaining health.You can also keep nuts with you which are rich in protein and healthy fats and keeps you full so you do not tend to eat more on particular timings.
# Start your day with a good breakfast which will help you to kick start your metabolism and help you in being energetic.Eat short and frequent meals meals.Normally in cold seasons people tend to eat more so for that keep handy some healthy snacks and fruits with you.
# When the temperature get more cool you don't like to go out for walk and exercise.so for that you can do some exercises in home only like jogging,skipping,Lunges,stretching,squats,crunches and most interesting dancing which will not only help you in maintainig weight and fitness but will also help you in giving a good warm up and will help in preventing you from cold.Also you can do is Yoga asana's,Take stairs instead of elevators,also you can involve yourself in household activities like cleaning,dusting decorating home.So all these tips will help you in getting proper fitness and maintaing health.