Question to general practitioner Maarten: Problems with bowel movements, problems with constipation

On average 2x a week I have serious problems with bowel movements, which in turn results in hemorrhoids. I eat 2 pieces of fruit every day, eat wholemeal bread and plenty of vegetables. Drink at least 3 liters of water per day and 4 liters in hot weather. Walk for 30 minutes every day and work in the garden for an hour a day.