Your life today is essentially the sum of your habits. That’s the point made by Atomic Habits author James Clear, and it is a good one. Are you out of shape? This is likely a result of your habits. Do you suffer from illness? This is likely a result of your habits. What you repeatedly do each day ultimately forms the person you are.

What if you want the person you are to become better?

You have free will and the ability to reason. Yet as much as 40 percent of your daily actions occur from habits that you do not actively think about. Harmful diet, inactivity, uncontrolled use of medicines, and other bad choices quickly become routine and cause great harm over time. This is why disease, which is abnormal, is considered so normal. But you can use these seven keys to break destructive habits and change your life, one day at a time.

Visualize your goal. At the beginning of your journey, connect your mind to the end. Visualize where you will be standing after completing your journey to replace a destructive habit with a healthy one. Once you go there in your mind, it becomes far easier to go there in your body. A crystal-clear vision of your goal will help you resist old habits, avoid distractions, prioritize your decisions, and motivate you to face the challenges.

State your mission. Write a mission statement to specify your goal, when you want to achieve it and how you want to achieve it. Make it crystal clear, strong and assertive, with measurable, attainable goals (see PossibilityChange.com). This statement might say: “I will build long-term health by exercising three times a week every week for six months, and by avoiding any foods that are harmful to my body. I will lose 20 pounds and feel noticeably better.”

Focus and refocus. The most successful people on this planet are highly focused. They pay attention to clear, singular goals. The habit of concentration makes you fully engaged in what you are doing. You get more done properly and deal with adverse life events better. The Power of Less author Leo Babauta writes, “If you can maintain your focus on a goal or habit, you will more often than not achieve that goal or create that habit.” Life throws a lot of distractions your way, dividing your time between many things and disrupting your focus. Eliminate distractions, and even eliminate other less-important goals, to focus on your main goals.

Set micro-goals. It’s good to dream big, but not so big that the goal is unattainable. Atomic Habits discusses a principle called “aggregation of marginal gains.” Instead of fixating on leaps forward in your lifestyle, settle on smaller habits that you can achieve and sustain—milestones on the way to your larger goals. These should be goals you can achieve within 30 days. Losing 6 to 8 pounds in a month, for example, is a reasonable micro-goal. Achieving these smaller goals gives you confidence, motivation and the power to achieve larger goals.

Punch through discomfort. We dislike disruptions to our habits and dislike physical discomfort. But if you give yourself no room to change, no room to fail, you give yourself no room to grow. Exercise is such a scenario, because building fitness and health involves disruption, not to mention aching muscles. But if you’re pursuing healthy, attainable goals, this discomfort is not destructive: It’s a signal that your body is waking up and becoming stronger! You can punch through the tiredness you feel. Doing so will help you reevaluate your relationship with discomfort: It’s a sign of achievement, a cue that motivates you even more.

Master your time. Effective time management goes deeper than just listing your tasks. It means transforming what your priorities are and developing self-control. Mastering your present time will help you achieve all your goals. For example, daily workouts and good nutrition may not seem urgent today, but accomplishing them circumvents negative consequences tomorrow. When you take control of your daily hours, you will find that your progress toward goals increases. Time management is not about getting things done in haste, but it certainly reduces wasted time and energy so you reach your goals quicker.

Build your willpower. Are you exercising three times a week? Are you cutting out sugary drinks? Are you avoiding evening snacks? Whatever your goal, you must exert willpower. Some days, self-control will feel beyond reach. How do you strengthen your resolve? Many people think willpower is a somewhat mysterious quality, but it’s a skill you can build with diligence. Just as a physical muscle grows from exertion, willpower (your mental muscle) builds through any regular act of self-control. To be truly successful, you have to flex this mental muscle over and over.

You are neither too out of shape nor too old to take on this worthy challenge. Take that habit you’ve been wanting to build and don’t let it go. See it, define it, concentrate on it, break it down, push through it, use your time, and exert your willpower. If you fail, come straight back and keep pushing and flexing these habits of health and of character.