I know this for a fact because I did it and you can too. Perhaps you are not looking to double your income, but just need to set some writing goals for yourself to keep your career on track. You may want to commit to finding a new market each week, or sending out two queries a day. Whatever your goals are, you can achieve them with some serious self-earned dedication. Don't get discouraged if it takes months to achieve your goals or if you achieve your goals one month and not the next.
Life happens, and sometimes life gets in the way.
Organize your priorities Assuming that your family is the first priority in your life, your writing career should be your second priority if your life if you are seeking success at it. If you have a job outside the home other than writing, you may need to focus on writing as number three on your list. As long as writing stays in the top percentage range of your priority list, you'll do fine. Don't put it on the back burner. Let your friends and family members know that you are giving your writing career the serious commitment it deserves.