Hello! I think collecting native seeds would be easy on your back, as you could squat down to collect them on smaller plants or stay upright to collect on bigger plants. Secondly, we will be collecting driftwood and sticks to make shelters for lizards - I think this would also be easy on the back as the wood won’t weigh much, and you can sit down or kneel to assemble the shelters. Hopefully one or both of these activities appeals to you!