how do you actually make yourself start the thing when your brain will do literally anything else

this isnt a focus problem for me cause once im in im fine, its the starting. ill have something i know i need to do and suddenly 10 other things feel urgent. clean my room, reorganize files, “research,” get a snack. anything but the actual hard thing. and none of its even fun im just avoiding it. whats weird is im disciplined in other areas. i hoop, ill build projects for hours, turned my socials off months ago and stuck with it no problem. but this one specific thing, sitting down and starting when i dont want to, i lose every time. and willpower doesnt help cause by the time im “deciding” ive already picked up my phone. so whats the actual system. is it a time thing like commit to 5 min, is it removing the escape options, body doubling, something with how you plan the day. not looking for the "just do it" answers cause if that worked id have done it. more the actual mechanic that got you to start when your brain was fighting you.