working out

for those who work out everyday how did you start? how did you motivate yourself to do it? I have 4 kids. 5'7 200lbs I want to lose 40-50lbs & be able to be happy with myself again but it's so hard to find the motivation when I'm so tired all of the time lol & I can't go to the gym bc my SO works 1st shift & I work 3rd