If you could give one piece of advice to a very smart but lazy guy, what would it be? originally appeared on Quora – the knowledge sharing network where compelling questions are answered by people with unique insights.

Answer by Graeme Austen on Quora:

If you truly want to go from lazy to motivated in all aspects of your life, you should do one thing, and one thing only:

Exercise.

Why? Because exercise is measurable, it doesn’t take a lot of time, and it creates a cascade that will trickle down into all of the other aspects of your life.

Let me explain (and show you how to easily make it a habit)!

Why Just One Thing?

Studies show that when people focus on changing a single behavior at a time, the likelihood that they’ll retain their new habit for a year or more is around 80 percent.

And those who try to change two or more behaviors at once? Success rates drop as low as 20 percent.

Why Exercise?

Two reasons.

First, exercise doesn’t require a large time investment. The Mayo Clinic recommends 20 minutes of exercise per day. Instead of hopping on Instagram or your email first thing in the morning — do this … then hop on Instagram.

Second, exercise is a keystone habit. If you’re not familiar, keystone habits are good habits that lead to the development of other good habits (made popular by Charles Duhigg in his book The Power of Habit).

Here is an excerpt from the book on exercise:

“When people start habitually exercising, even as infrequently as once a week, they start changing other, unrelated patterns in their lives, often unknowingly. Typically people who exercise start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. It’s not completely clear why … ‘Exercise spills over,’ said James Prochaska, a University of Rhode Island researcher. ‘There’s something about it that makes other good habits easier.'” (p. 109)

How Do You Make It a Habit?

Habits have 3 components: a cue, a routine, and a reward.

The most important parts of this loop are the cue and the reward. In fact, you’ll have an easier time adopting the habit if you choose a cue and a reward that already exist.

Let’s say that when you wake up (cue) the first thing you do is check Instagram and then you have your morning cup of coffee (reward).

Tonight, put your workout clothes next to your phone. Tomorrow, when you wake up, immediately put them on and go perform your exercise. Then have your cup of coffee (or check Instagram, whatever is more satisfying).

A personal anecdote: When I was trying to make running a habit, I promised myself a beer at the end of the day if I completed my mileage goal. Worked like a charm.

In summary:

Step 1 – Identify a cue and a reward. Insert exercise in between.

Step 2 – Create a schedule for your 20 minutes each day and follow it religiously for the next 30 days (pro tip: doing it first thing in the morning makes it much easier to stick with).

Step 3 – Profit.

Make It Measurable.

Before you start, weigh yourself. Then, during or after your workout, document exactly what you did (miles ran or exercises performed + weight for each, etc.).

Then continue to weigh yourself each week and bask in your progress!

Once you hit the 45-day mark, feel free to take on other personal challenges.