Be a Smiling Person Yourself
It can really sap positive energy to be constantly nitpicking another person all the time -- and dealing with his or her potentially negative resulting reactions -- so lay off any nagging you might feel like dredging up and see what happens as a result. It can prove to be a serious mood lifter. Not all close relationships will see felicitous outcomes, but many will. Constantly worrying about every little thing in life (especially if a mile-high to-do list is involved) can trigger negative emotions that are easy to transfer to the people you love in your life.
To get things rolling, why not take a second look at the dynamics of your relationships and your goals for them, whether those relationships are with your partner, siblings, children, parents or roommates? See if there are areas where you could lighten up a bit and work in a little happiness instead. Will it really matter if the laundry/dishes/dusting is accomplished this exact second? Could you both squeeze in a few minutes together laughing on the couch or companionably going for a walk? Most chores can wait -- up to a point. Spending time with the people you care about is precious indeed. Not only will these people tend to be happier, you won't be expending so much energy trying to micromanage your own expectations. And those two factors can definitely help lift a person's mood.