Start by doing just one thing at a time in your daily life.
If you are driving, then just drive – no music, no talking on your cell phone. If you are waiting in line at the grocery store, just wait in line – no texting, no flipping through magazines. If you are watching a movie, pay attention to the movie. If you are having a conversation with someone, really focus on just that conversation.
Notice when your mind starts to wander to thoughts that aren't directly tied to the present moment and gently bring them back.
Here is an example of standing in line at the grocery store checkout.
I am standing in line. I feel my purse on my shoulder. There is a breeze whenever someone enters or exits from the automatic doors. I hear "beep, beep, beep" from the cashier's scanning device. My alarm clock's beep is kind of annoying - wait! my alarm clock isn't here. Here I am putting apples on the checkout counter. The box of pasta is blue. The mac-n-cheese at Rubin's is the best... with the pancetta. Their beer is so good, too. Wait! I am here. I am getting out my wallet and removing my credit card. I slide it...At first your mind will jump to the past and the future and to other thoughts every few seconds. This is totally normal. Just keep practicing. Eventually, you'll find that you can maintain focus on the present for longer and longer.
This is the essence of a meditation practice.