Positive thoughts lead to positive lives. Unfortunately we cannot always say YES. But instead of stating a straight out NO… try to reword your sentence directing the energy and focus in a positive forward thinking direction.
For example a friend asks you to join her for lunch. Instead of stating, “No I don’t have any time. I never have any time for myself.” I am sure you can see where this conversation can end up. State, “Oh thank you so much for the invite. I would absolutely love to but I am booked for the day. When are you next available to get together?” This type of answer keeps the conversation in the positive mindset and moves you into a forward thinking mindset as you are planning for the next get together.