Lots of people have given mindfulness a go, but they don't really understand why it's important and how mindfulness helps. So let me explain to you the reasoning behind mindfulness.
Imagine a mouse walks into the room right now and I say the word 'cat'. Is the mouse going to feel scared? No, because the mouse doesn't have language so it doesn't understand that the word 'cat' represents danger. The mouse will not feel fear in the way that a human might if i shouted 'fire' or 'help, intruder' or 'snake'! The mouse won't feel fear in response to a word. If the mouse comes into the room and it sees a cat is physically present - it's going to feel fear and it's going to run away (flight) or freeze. The mouse is living in the present moment. The here and now.
Small children are like the mouse. They live in the present moment. Imagine a 2 year old walking down the street. The toddler is going to stop and look at everything in wonder. It's going to be a slow walk. The child is there, in the present moment. They're not going to be upset about what happened yesterday (regrets about the past) or worried about what's going to happen tomorrow (what ifs about the future). The child is not going to be thinking "oh, I shouldn't have said that to mum yesterday" or "Oh no, what if it rains tomorrow and I can't go to the park". The child, like the mouse, is going to be in the present moment. They are only going to be upset if there is a here and now trigger. Like hunger, tiredness, thirst, or there's a big dog and they're scared.
Adult humans apparently spend 32% of our time either thinking about the past or the future. So on average we are in the present moment only 68% of the time. In life, we want to be more like the two year old. Adult humans, have language and can therefore dwell on regrets from the past. Repeatedly going over events from the past can cause us to feel sad and regret. We tend to have a bias to recall negative events from the past over positive memories. We are more likely to have negative thoughts about the future and think about all the things that might go wrong (catastrophising or what ifs). Worrying about things that might happen in the future cause us to feel stress, fear, and anxiety.
So, that's why we need to try and be more like the two-year-old (or the mouse) and stay in the present moment. Ultimately, we don't really know (and we can't control) what's going to happen in the future. We can't change what's happened in the past. So today, try and be more like the two year old. Be in the present moment - looking at everything around you with an attitude of openness and curiosity and wonder (just like a small child). As though it's the very first time you've ever seen the world.