Is nls lifeguarding course hard

Answer 1

It's not "hard", but you need to know your material really well. There's no written test like Bronze Medallion or Cross but you should still know everything as you will be using it in situations.

You should also be physically strong. Physical requirements include swimming 400m (16 lengths) in 10 minutes or less, swimming 15m underwater (fully submerged), head up swimming for 2 lengths in a minute or less, swimming 15m then going down to the bottom and picking up a 20lb brick and then swimming 10m to the end of the wall while keeping your entire face above the water, among many others (there's 10 in total I believe)

If it's your first time doing the course and you haven't swam in a while, I wouldn't recommend doing the 1 week crash courses they offer. You need to do everything perfectly in order for them to pass you, and 1 week just isn't enough to understand all the material imho.