Meditation is not always relaxing of course. In mindfulness meditation you learn to observe your thoughts and feelings from a calm center. This is not always comfortable.

I think the mantra style meditations are perhaps the easiest and most instantly relaxing. You could try out this one ..

Sit comfortably.
Consciously relax your muscles from your toes to the tip of your head.
Say the word “One” silently in your mind.
Say it gently. There’s no need to mouth it or force it.
It should just be a gentle suggestion in your mind.
Don’t make any effort.
Don’t worry if you stop saying the word for a while.

Continue for 10 minutes – See how relaxation really feels!