I like to go for a walk at lunch, get some fresh air. If I've bought a lunch then I go to the park to eat while walking around, if I'm buying then I pick a slightly further away place.
It is worth seeing if you get used to it though, everyone struggles with a full time job to start with, especially if it's a starter job, low effort, repetitive, probably below you in the long term. As you get into a routine it gets better, adding responsibilities makes it better, even getting to know people so you have more chats makes it better.