i had a similar experience i was at home trying to do a paper i couldnt do it for the life of me kept getting up doing dishes fiddling with random things etc you know the deal typical adhd things  then my fiance comes and asks how im doing i tell her the whole thing she tells me  why dont you go sit somewhere quiet and just focus  it never hit me before all i had to do was just focus eureka  since then whenever i need to do something i just remember to focus and - boom i can do it no problem who would think that the only thing i needed to was just focus