I learned a long time ago that food is the number one thing I foolishly spent my money and wondered where all my expenses were going. Not much can be done about the preschool costs (I feel the pain there), but the very least you can do is create a food budget, go to the grocery store, meal-prep, and replace common expensive things like coffee/smoothies and make them at home. After about a few months of adjusting to new behavior constraints you start to optimize and learn new habits that turn out to be more comfortable to work with. (Bonus: I now enjoy cooking). If you still enjoy the odd day going out somewhere to work, never leave home without a tumbler or some canteen of some kind.