why is it so hard to let go?

we were together for almost a year & we just broke up 2 weeks ago & im tired of being sad over it because i’ve realized that there is nothing i can do to get him back. do y’all have any tips on how to heal from a break up? i know it takes time, but it feels like this is gonna last forever. literally everything i do reminds me of him & it’s starting to get annoying lmao