Sit down and take some of the weight of the instrument by resting one end on your knee. Or if that feels too cramped, get a lanyard (length of string with loops at both ends), attach to concertina using the screw-in buttons on top of the thumb-straps and hang the thing round your neck. If guitarists can do it, so can we!!

Keep going - there can never be too many concertinas being played in this world!

Andrew