There are some GREAT responses here - but I'll try to add another.
My husgand and I met almost 20 years ago. We've been married for 15 and have 2 little girls (7 and 2). When I was a kid, my parents were separated for 3 years - the only reason they didn't get divorced is because my Dad just never got around to signing the papers. This is just so you can get a feel for me.
I am "hapily married" but, it's because I choose to be. I think that people watch TV and/or movies and read books that all end with "happily ever after" and think that is how life really is and that there is no effort involved. And that's wrong.
Every morning, I get up early and have an hour alone. I eat breakfast, I surf the net, I make coffee, and I shower. This is my "me time" and I need it for my sanity. Because at 6:30, things start getting nuts and I've got demands on me from everywhere (every Mom does, I think). My "alone time" centers me - it lets me be me for a little while.
My husband and I had some hard times and I thought about divorce. But, that seemed like quitting to me, and I've never been a quitter, so I would jump back in and go again.
So, I started to look for the good things in our relationship and about my husband. My guy is not actually thoughtful nor is he romantic. No thinking ahead for him - my guy is the dude out at the grocery at 9 p.m. on Valentiene's Day muttering "Crap, I forgot to get something for my wife". So, anything he does that is nice is great!
I tell you that to say that it's not the huge romantic gestures that are the important ones. Sometimes, when he goes to get a lottery ticket, he will bring me my favorite candy bar. I know that may sound silly, but that shows that he's thinking of ME, and it is a way for him to show he cares.
We have time to talk. When he comes home from work every day, I ask how his day was. I used to get bent that he didn't respond in kind. But, again, something that he has had to learn. It also took him YEARS to say something other than "ok" but with a lot of prying from me, we've progressed.
My Mom used to call him a stick in the mud. And, he was. My siblings, parents and I are pretty physical (we wrestle over everything!) when we're together and we laugh over EVERYTHING! My husband has only is the last year gotten to the point where he will joke back! He's probably still a stick in the mud, but he's getting there.
My mother went to see a counselor when I was in my teens. She was depressed and needed to talk to someone. This was a Christian counselor and he told her this: "Everyone thinks that the family that prays together stays together. That's not entirely true. I've found that the family that PLAYS together stays together." So, we goof off some. We used to play card games before bed. But now that we have kids, we wrestle some and tease A LOT.
I know these things don't sound like much, but they are important. And I can honestly say I'm more happy now than I've been since our first year of marriage.
I wish there was some magic words to say. I think that what works to make one marriage happy is not always what will work for the next marriage. And, I think that sometimes we get a "the grass is greener..." attitude. I guess my suggestion would be to read all the responses and to pick things that sound like you can do them and try it. You've been married 10 years - for a lot of people, that's forever!
One last thing. Hubby and I have gone thru years where we were just roommates. You know, we live in the same house. We didn't really talk - or if we did, it was like pulling teeth. I think every marriage has times that are not the "happily married" times. Just take the time to sit with your man and tell him what's going on with you - you might be surprised at his response!