If you catch yourself in deep thought about someone throughout your day-to-day living, your initial reaction may be to force yourself to stop. However, studies how shown that suppressing uncomfortable thoughts and/or feelings can lead to them returning stronger than ever, according to Healthline.
Hence the best course of action to take in this situation is to dive deep and figure out just why you're pondering so much. Here are some possible reasons: (1) you are in love, (2) you are insanely sexually attracted to said person, (3) they are giving you mixed signals that have left you overthinking, (4) you are an avid daydreamer fixating on unrealized hopes, (5) you are in a relationship but unsure of where it's heading, (6) your love is unrequited.
There are many other potential reasons, but only you can identify them (and if you find your introspection yielding no results, therapy can be a great place to start).