You can make a monthly menu. It isn't as hard as you think. Just sit down with a piece of paper. Make two columns, one for the meal and one for the ingredients. Flip the paper over and write down every meal that your family likes that you make. Dig through your cookbooks to jog your memory. Ask your family. Shoot for 20 meals. Yes, you CAN think of 20 meals. You probably have more than you think.
Then flip your paper back over to the two columns and divide the meals up into 5 choices for each week. 4 weeks for each month. You could also do just a 31 day menu if that works better for you. I don't plan for weekends because we get Angel Food Ministries food (http://www.angelfoodministries.com/) and cook off of what we get in our box for the month. We also eat out from time to time on the weekend.
Making your grocery list is a snap. You already have the list, just check your kitchen to see what is missing. I use coupons and look for sales. I buy more than one if it is on sale and then it is in my pantry for next month.
There isn't that nagging question all day about what you will cook. You can even do a little prep in the morning and defrost your meat or chop one of your vegetables. If it is crock pot friendly, start your meal. You won't ever go to the grocery store and come back with nothing to eat. You will eat healthier because you will eat out less. You will save money because you will buy just what you need and avoid spending money on eating out as often.