Plain yogurt is best. You can also use acidophilus supplements which can greatly increase the amount of bacteria without having to eat tons of yogurt. No amount of supplementation or fibre can make up for poor diet. Try to minimize your exposure processed foods and sugars. Instead rely more on whole foods and vegetables.
Sufficient exercise stimulates the colon and aids in elimination.
In addition exercise also has many other benefits such as improved mood and stress reduction. Yes, we said mental health. How you are dealing with stress or the emotions you experience on a daily basis can play a huge factor in health. No one can doubt that stress can effect sleep, immunity, and digestion. So take some time for yourself.