Great responses! I have done assorted merchandising tasks. These are great for me, generally. The ones with lots of standing are a real pain the the back. But that is just me. I love the variety, the fact that many gigs are finished fairly quickly, and the jobs can be combined with audits, shops, personal tasks, etc. I have my little ways of dealing with the back at work. Other people do what they need to do for themselves.
For someone with anxiety, it might be a good idea to think about embedding buffers into their schedule. To offset work stress, they might give themselves quiet time, rest time, fun time, or whatever makes their unique equation work. Some things that 'might' make a newbie antsy include: waiting to get checked in before starting the job (during this time, the sense of preparedness and readiness might slip away); feeling unprepared for various details of a first-time effort/text anxiety (all those details are not sitting still in the mind but are running about like wild animals who've escaped the zoo!); and concern about making a mistake (money and time might be wasted, or self-esteem could plummet). Your relative can alleviate some of these concerns by giving themselves time to study and review, doing one job at a time, doing multiples of one task type, or whatever little tricks they devise that can minimize terror and increase comfort.
Some of us love merchandising. I hope that your relative will give themselves a real chance to find out if they would like to do some of this work. :
Those who wish to sing, always find a song. -Swedish proverb