John Gottman says there are just four prescriptions for a happy marriage:

1. Turn toward your partner (both physically and psychologically).
2. Say positive things.
3. Celebrate the hard times you’ve been through.
4. Look at the Goldfinch (look if your partner says there’s a Goldfinch in the backyard).

The good thing is that these simple steps are within your control.  They are not hard to define like a “spark” or “that special something.”