Hi Jn49,

It may feel weird at first to hold a guitar since you're not used to it. Make sure your shoulder is relaxed, and you're relaxed overall. It may help if you're sitting down as well.

since you're doing the spider-legs exercise, you must have gone through the first chapter of Guitar fundamentals level 1 already but make sure to watch the lessons again on how to hold a guitar if needed. Check it out here: https://www.guitartricks.com/tutorial.php?input=1766

And when you say your forearms are feeling tight, it might be because your wrist is bent too much? Let me know what you think and make sure you keep your arms relaxed!

Best,

Billy