If you think you will be happy tomorrow, remember that tomorrow never arrives.
Don't put your happiness off until a point in the future. Today is a gift from God. Treat it that way. It is okay to plan for tomorrow, but not at the expense of enjoying today.
If that is how God clothes the grass of the field, which is here today and tomorrow is thrown into the fire, will he not much more clothe you, O you of little faith?