Aloha Artimuse,
Getting enough sleep?
The "drifting" can be from a lot of things. This all changes as you do the work. Be okay with the drifting and resume as you would if a "grocery list item came to mind during a meditation.
Bending forward with a slight bend in your spine and patting your tail bone/sacrum area for 2-3 minutes before and after your exercises/meditations can help open up the sacral area.
Much Love, Shawn