I am always looking for ways to make my life both more productive and less stressful at the same time, and since I spend most of my working day at the computer, much of that effort has to do with how I use the computer (and iPad and phone, these days). But the issue isn’t whether or not you use the keyboard and mouse; the issue is what you use them for. I think there’s nothing wrong with using your mouse to scroll through an article you are reading — that’s how you learn things, and I find reading relaxing, even at a computer. The challenge is suppressing all the other ways your computer can bother you, or all the impulses to do something else, of which checking your email is probably number one.
I’ve tried a lot of tricks over the years. The problem is finding something effective that you can actually stick to. My current number one trick, which has worked well for several weeks now, is that I only check email between 10 and 6, Monday through Saturday, and when I’m not actively checking and responding to email, I close the window. It doesn’t work perfectly — I still check too often during the day — but it works pretty well. Basically, if it’s before 10 or after 6, I just pretend the email doesn’t exist.