You get strong by doing things. It's really that simple.
Let's say you wanted to run a marathon for example, not that I ever have. Taking a daily nap night not be the best way to train for it. You have to actually run. You have to make yourself run just a little bit farther when you are already tired and want to quit. You have to run a little farther and faster than you did the day before and you have to do it every day. This is how your body gets stronger, gains endurance, and you get to the point where you can finish running miles and miles without embarrassing yourself by falling over and dying halfway through.
Motherhood isn't that much different.
Those moms you see who seem to do everything well in ways you find impossible to even imagine, they started just like you with one little tiny baby and no idea what came next. The beauty of motherhood is that it comes in stages. At first all you really need to know is how to feed them, help them sleep and keep them clean. You can handle that.
You don't need to have the next 18 years figured out. Heck, not even the whole first year. You can do this one day at a time. You keep your head down and you keep trying and every day you can go a little further, and you'll find you are a little bit stronger than the day before.
Some time after your baby is born you will triumphantly find that you have finished a load of laundry and made dinner, all with a newborn in tow.
A few years down the road you may have more children and someone will offer to take the older ones for a day while you stay home with the baby. You will be so excited for the rest because after having more children you realize that a day at home alone with just the baby is like a vacation compared to having several others around too. You will get so much done that day. You will wonder why this all seemed so much harder the first time around. Then you will realize that you are stronger.
The secret? Don't try to escape.
That's like taking a nap when you should be running. This is like trying to get away from the labor that will bring the baby to you. The only way out is through. Mom time and me time sound nice, in theory, and it is important to make sure we take care of ourselves. But "me time" doesn't strengthen you. It doesn't make you better able to cope with what you have to do as a mom, day, after day, after day. If you haven't rolled up your sleeves and put in the effort to learn how to be the mother you want to be to your kids, time away doesn't really give you anything at all, except maybe the desire to have even more time away and the perspective that our family and real life are an annoyance and an interruption to your preferred life of time away. (This is not to say don't take rests or breaks to refresh and recharge once in a while, just to put them into perspective for you.)
You have to learn how to work caring for yourself, your body, your mind and your spirit into the every day of taking care of your children too. Maybe that means strapping the baby on and going for a long walk and praying as you move to keep the baby soothed and your heart connected. Maybe it means going out to visit friends less so you can have more time at home to find a routine. You will have to figure that part out.
If you keep at it, keep trying to gracefully perform what is given to you to do, you may look up several years down the road and realize that other people are looking at you wondering how you manage to do what you do, and thinking to themselves that they could never do that so well. You can smile and know deep down that you are far stronger than you could have ever become with out these children you mother, for every day they made you run an extra mile and all those miles have brought you here.