That’ll only take 11.5 days. Get to work!

You want to keep clicking that mouse until you burn one kilocalorie? Fine. Be my guest. You’ll have to click it 10 million times. Clicking 10 times a second (which seems pretty fast), you’ll be click-click-clicking away for 1 million seconds. That’s 11.5 days. I’m pretty sure you would burn more energy breathing. Ultimately, this value of one big calorie per click simply isn’t going to work.

Source: You’d Have to Click a Mouse 10 Million Times to Burn One Calorie | WIRED