If it seems overwhelming, maybe you could start small - one meal at a time.
For example for the next few weeks you could make sure you have a decent healthy breakfast. Porridge with fruits and nuts is an easy option. I usually have it with blueberries (I keep lots of frozen fruit in the freezer which I also use for fruit smoothies) and some chopped walnuts with a bit of honey - filling and delicious. Or you could try it with banana and cinnamon. Now that the weather is getting better you could add in some strawberries when they are in season. Find a combination you like.
Or if you prefer a savoury breakfast some scrambled eggs with a few veggies, or an omelette. Or wholegrain toast with peanut butter and banana and a fruit smoothie.
After a few weeks when you get used to your breakfast routine, start to swap out some other meals for healthier versions.
If you have time at the weekend, cook a large batch of healthy vegetable soup and freeze it in portions which you could have for lunch.
You could also try using wholegrain bread, pasta, and brown rice instead of white - they have more fibre and keep you fuller.
For dinner, try adding more vegetables to your plate instead of potatoes etc.
After a while you will feel better and hopefully it should spur you on to keep going.
Also, try to have healthier snacks on hand during the day - nuts are a great one, so is fruit and greek yoghurts, rice cakes with peanut butter, a few slices of cheese or a hard boiled egg.
Instead of thinking of it as depriving yourself, think of it as fuelling your body in a positive way.