I've always loved vegetables and conventionally "healthy" things, but admittedly, the majority of my diet was made up of quick, easy foods that came from boxes or were heavy on carbs but low on the nutritional scale.
With keto — while there are no real restrictions on what you can and can't eat as long as it falls within your macros (the amount of calories, carbs, protein, fat, etc. you should be eating per day) — the general idea is to start eating foods that are what they say they are instead of options that are made up of a long list of ingredients you can't pronounce.
That means lots of fresh veggies, lean and fatty meats, eggs, cheese, and even butter. Fruit has also become part of my diet in moderation, though I stick with low-sugar varieties like raspberries and blueberries over higher carb options, such as pineapples and bananas.