Live the moment is not any heavy word to implement in life but simply means letting go of the past and not waiting for the future to explore ways to celebrate present.
When we live in the present we enjoy the moment and explore so many opportunities around us which we never considered earlier because most of the time humans are traveling in their self-created time machines some are traveling in the past while others are in the future.
The very few of this mankind who choose to be present fully explore their potentials and gifted our new inventions, discoveries, etc. They are not different from whom we call great souls/genius brains but they are the people who choose to be present and live the moment. e.g when the teacher is teaching in the class a very new concept the students who have connected with teachers wavelength and the flow of the concept understand for the lifetime without much effort other than students who are least interested in the class but focus on the time to get class over.
Live the moment is to connect with the surroundings we are: if sitting feels the chair, room temperature, breathing, etc.
Shift your focus to where you are right now and what best you can get from there to feel happy…Live the moment is a skill that can be developed by mantra practice, practice, and only practice.