There's an in between though mate. Tesco is a bit extreme. I completely agree that if you aren't enjoying your job and it's causing unnecessary ongoing stress then you should find somewhere else. We spent most of our lives working we should ****ing enjoy it.
But if you work at Tesco from your current position, the stress will probably be replaced with depression. You can easily find a less stressful job that's less well paid but still respectable and requires responsibility. Like I said there's an in between.
And as someone who has worked at Tesco, yeah it wasn't bad part time but it would be a nightmare full time. A lot of the customers are lovely but some seriously treat you like you sub-human, with your only role in life being to serve.