Whatever you consider to be "normal" eating and "not on an actual diet".
A diet is just what you eat habitually per definition:
a : food and drink regularly provided or consumed
b : habitual nourishment
c : the kind and amount of food prescribed for a person or animal for a special reason
d : a regimen of eating and drinking sparingly so as to reduce one's weight <going on a diet>
Now..you already cut out sugary drings, which is a huge step, depending on what amounts you used to drink. And maybe what you consider "normal" food is already quite sensible, so working out does the rest.
After all, it is NOT all about calories in and calories out. If it was you could just eat 100 grams of sugar and 100 grams of fat per day and thrive on those 1800 cals. But nobody here will tell you that is a good idea.