Here are some easy steps that you can follow to build those habits such as doing exercise, spending time with kids, cooking rather than eating outside, eating raw fruits/vegetables, meditation and so on.
The key to making any activity a habit is by doing it consistently at the same time every day for 21 consecutive days.
Since you know a healthy habit has its formidable advantages, set a time for the activity so that you do it at the same time every day; push it to top priority and forget about everything else until you complete the activity. Don't time the activity until it becomes a habit (21 consecutive days). After you complete the activity, reward yourself.
After doing it regularly at the same time for 21 consecutive days, it automatically becomes a habit. It's like waking up at the same time by setting an alarm -- after few days, it becomes a habit and your mind clock would wake you up at the same time without an alarm. It's that simple. You just need to tune your mind to completely focus on finishing the activity so that your mind doesn't wander thinking about several other tasks at the same time. Tell yourself that everything else is temporary and what you are doing is going to make you very happy.
Remember, same time every day for 21 consecutive days. Your kids will follow you automatically without even advising them; they watch you and learn. Wishing you healthy and happy living!
Keep smiling :)