By learning to master your internal "self-talk" throughout the day.
"Change your thoughts change your life."
The challenge however is just about everyone from family, employers, co-workers, friends, loved ones, and the news media/marketers are all clamoring to get you to think or focus on things (they) want you to think about. In other instances when things aren't going our way we become negative and think about all the other times we didn't get what we wanted.
The most successful people usually carve out some "quiet time" for themselves first thing in the morning. Whether it's meditation, visualizing achieving their goals, or feeding their mind by repeating affirmations. Essentially they're proactively choosing to think about what (they) want.
Some people find time throughout the day to pump themselves up. Should something negative pop up in their mind they quickly say; "Cancel, cancel."
The belief is your subconscious acts on your behalf whether you feed it a negative thought or a positive thought.
You can't live your life on autopilot.
Always (be conscious of what you tell yourself). It's been reported that just before falling asleep and upon awakening are the best times to feed your mind with the thoughts and visions of the life you want. Some people create dream boards with pictures.
Author/speaker Neville Goddard taught people to (imagine) already having what they want in life and experiencing the (feeling) they would have if it was real over and over again.
"I am the greatest, I said that even before I knew I was."
- Muhammad Ali