Understabding that it is when the nature of mind is either in rajas (forceful) or tamas (dull) that there are vrittis (thought waves) that are not useful for our development/evolvement, (working into the boat pose with this).
This can cause doubt and anxiety because we do not have a sattvic mind (- calm, cheerful).
Only when body mind and intelligence are purified (-sattvic- calm, open, bright) we can surrender and not expect anything in return; this is the mastery over the mind and anything presented to mind then can just shine back to the object. Ref Patanjali 1,36 140, 1,41
Om Shanti