My dd is almost 7 and we were starting to have some issues with the same things. Here's what worked for us:
Moving around! We go from the couch to the white board to a table....
Snack time. I don't normally do a morning snack, but have found if I say we are going downstairs for a snack after we finish A, B, and C then she stays focused and gets it done.
Stars! If she stays focused on her work then she gets to pick a marker and I put a star or happy face on her hand. Motivation for her and no effort for me. Its a win win!
Finally, I found that if we start our work with a read aloud that SHE picks then she is more willingly to work for me later on. This has the added bonus of giving my 3 year old son a story before I want him to entertain himself for a while.
Good luck!