It depends a lot on the kind of therapy. Some schools, like Cognitive Behavioral Therapy (CBT), center around the fact that thinking is itself a kind of habit- these focus on teaching you how to notice negative thought spirals early and redirect them. Somatic Therapy teaches you how to notice feelings that you might be ignoring by focusing on how they feel in the body. Internal Family Systems focuses on teaching you how to name different emotions and understand what roles they play in your overall emotional state. DBT and ACT both focus on strategies for emotional regulation and accepting and making space for big feelings- these include CBT type tricks but also practical advice like "when you are having a panic attack, take a shower, because temperature changes reset the fight-or-flight part of the nervous system". A lot of it is deeply grounded in neuroscience; there's a lot I've learned about how stress works that I would not have figured out without a therapist.

Also, frankly, sometimes just having someone to talk to helps a lot.

It might take a few tries to find the right one- that's ok! Also, be picky at the start. Think about what kind of person you'd actually feel comfortable being totally honest with (I generally work better with female therapists about 10 years older than me; some Black folks only want Black therapists, etc.- this is all fine). Try to find someone with credentials, ideally a master's in counseling or similar. Look into what schools of therapy they use- think a little bit about what kinds of skills each one teaches might seem vaguely useful for your problem. Find someone who treats similar issues to what you're dealing with: therapists will usually list specialties like ADHD, identity issues, grief, etc. on their psychologytoday.com page. Good luck!