Keeping Relationship Alive

We all would like to be a part of healthy, fulfilling, long-lasting relationship, which is fresh and enjoyable as if we remained 20 years old folks.
Since last year I am attending the therapeutic sessions here in New Jersey organized by dr Janet Crain. On one of the sessions she told me an interesting story.... One day in December last year, short before Christmas she had a visit of a woman- middle age, attractive female with positive outlook and life attitude... Nobody would say that something might be wrong with her life....at least it didn`t look like...
But she actually had a problem.... She said...
"ok, me and my husband are a perfect couple from our friends` perspective...
I also feel that I couldn`t have a better husband, but I feel that with the passing time something is missing. Something is missing and is negatively and tremendously influencing our relationship..." and then she asked:
"HOW TO KEEP MY RELATIONSHIP ALIVE?"
Then we had a branstorming activity where everybody was encouraged to share thoughts on that with others....
As my parents divorced few years back, I have been thinking a lot about the question asked by this woman a lot. My parents didn`t really fight or something like that. I just have a feeling that their relationship was constantly dying and just finished one day...
I just don`t want my relationship to “die”. I want to learn from others mistakes. So I came up with some ideas but am also extremely looking forward to add your ideas into my list.

This is my list:
1. Appreciate your partner and show it to him.
2. Keep dating- at least one evening per week only for you!
3. Keep communicating- talk a lot, share problems, and challenges on a daily basis.
4. Remember beginning- remind yourself why do you love him/her.
5. Take risk and challenges together.
6. Take up a common hobby.
7. Organize "little surprises" for each other.

Any other ideas? Please share it with me....