The term ‘mindfulness’ is somewhat self-explanatory. At its very core mindfulness is about bringing awareness to yourself and your surroundings, both physically and mentally.
One of my favourites mindfulness exercises, is a very simple walking meditation. You can do this anywhere, from walking to the shops, to walking up the side of a mountain.
This walking meditation focuses on creating rhythm and using that as your focal point. It’s particularly great if you find yourself overthinking or overwhelmed.
It's really very simple, as you're walking, count each step in your head, when you get to 10, restart from 1. Keep your walking speed relatively slow and your pace consistent.
As you're counting, you should begin to feel a sense of inner focus. As you do, continue to count in your head but start becoming more aware of your surroundings. You don't need to dive too deeply into what you're seeing, simply observe it and note it. "oh, they're nice flowers", "nice colours", "haven’t noticed that before".
The great thing about this practice is that it ends whenever you want it to, but I really encourage you to continue to do it beyond what feels comfortable, to the point where it seems weird to still be counting your steps. This is when you'll most likely start to feel the difference.