Staying hard is difficult now

I work 2 jobs. One of the them I’m using my legs and arms all day until it’s time to go. I’m an order filler for Walmart and the other one I just clean the floor and the bathrooms , it’s a chilled job. Then throughout the week I watch my 2 girls who is 5 months and 3 years old. I wonder do my body be tired to keep up an erection now ?? I didn’t have a problem until I was watching my kids all day.