It does not mean you should pretend you're with your desired person all the time, although you can do it if it makes you happier.
Make yourself this question: how would you feel if you had your person right now?
Calmed? Peaceful? Relaxed? Relieved? Joyful?
Really explore those feelings and realize those feelings come from within you, not from anyone else or any outside experience.
Then, incorporate those feelings into your everyday life and just feel elated, excited. That's what it means to "act as if"
You can visualize each day if it makes you happy, but don't do it trying to make something happen becasuse it will make you obsses over it.