What you can change really depends on you. Once you have observed your own eating and drinking habits you will then see things which you might be able to change.
The change which you decide on could be very, very small. This is fine, in fact it is excellent. Proving to yourself that you can change could be the biggest step you take.
One way to approach your change is to list all the changes you could make, and then grade them on how easy you think they would be to put into action.
Here are some changes other people have made
Using a smaller bowl for cereal in the morning.
Having one slice of toast for breakfast rather than two.
Using less butter on their bread and toast.
reducing sugar in tea from two spoonfuls to one.
Once you have decided on what your action is going to be, you’re ready to go the next step.