It's a struggle some days

This whole being a mom, a wife, a housekeeper, and working from home is becoming a larger struggle than I thought it would be.
I figured, I am at home...the best place in the world to be; my mom never got to stay home when my dad left when I was 2 and I had wanted that so badly, so I am glad I have the chance to stay home with my little boy and offer him what I did not have! But to bring in a little money so I don't feel the guilt of my hubby supporting us and so we have some fun money, I decided last year to work for my mom from home. It went quite well so I tackled it again this year (the bulk of her work and heavy deadlines is Jan-June).
Well this year there is quite a bit more work, my little boy is quite a bit more active, I am trying to get my body in shape b/c I cannot bear to be this flabby and porky anymore, and still maintain a home and be there for my hubby!! It seems this week it's all becoming so overwhelming and I am starting to fall apart!!!!
How do the moms who have to get up in the morning, make themselves presentable, haul their kids to daycare, work a full 8 hrs, come home to dinner, kids, hubby, and perhaps a moment of peace, do it??? Honestly I feel ready to break!
Tomorrow I am taking a day to spend with my son and recoup my soul! I need it before I snap!