Intend for it to come. In our busy lives, we need to take time to intend and either silently or out loud say "I intend for happiness to come to me today." The universe will always listen to your intent. If this is what you choose to experience say it as it is already here. Be clear about your intention and don't doubt the statement you make, because words and thoughts have power.
Be aware of the simple things in life. The simple things in life that are free, are all around you. You can choose to be aware of them or not. But being aware of nature, your kids, the life you have will allow you to see your life in a more easier way, because you are taking time out to look for the good in the small things. These simple acts have a major positive impact on your day.
Let it in. It is important to accept happiness when it is trying to come to you, there are many times when we ask for it to come, but because we aren't alert or aware of it, we might miss it. Expect it to come in forms that you probably never even thought of, that's how it usually will come in anyway.