When the biggest happiness study of all time tracked more than 200 men for 75 years, what did it determine was the biggest driver of well-being and life satisfaction? In the pithy and poignant words of the study's original director: "Happiness is love. Full stop."

No wonder then that scientists have spent decades digging in to how to make romantic partnerships work. (If you're a more mercenary sort, I could also note that a strong partnership is also closely tied to career success.) All of this research has generated a library's worth of papers, reports, and articles.

The abundance of tips and recommendations is itself a challenge. In this sea of advice, which techniques and behaviors really have the most impact? Helpfully, University of Illinois Urbana-Champaign professor Brian Ogolsky has waded through more than 1,000 studies from 50 years of research on the subject, so you don't have to.

His efforts generated a massive 17 tips, which you can read all about in this Time article. But 17 is a lot to take on. Which tips are the best of the best? Further research done by Ogolsky and highlighted by PsyBlog has boiled it down to just five essential behaviors.

1. Openness

It probably won't come as much of a surprise to happy, long-term couples that reams of research suggest talking about your feelings and insisting your partner does the same is one of the keys of relationship success.

2. Positivity

Pessimism has its uses, but with my apologies to the naturally downcast, one of them does not appear to be supporting the health and happiness of romantic unions. The research review showed simply being upbeat and fun to be around goes a very long way towards keeping a relationship together. (If you're not naturally sunny, don't worry, science shows you can change if you want to.)

3. Assuring your partner you're committed

Don't just assume that because you're both wearing wedding rings or making joint mortgage payments, you don't need to constantly reiterate to your partner that you're in this thing for the long haul.

4. Shared tasks

Any long-term relationship is a joint project requiring effort from both parties, and that should be reflected in how you divide up day-to-day drudgery. Ogolsky stresses it's important to divide household chores and responsibilities equally.

5. Shared social network

Nope, not a joint Facebook account. This insight goes back years before the dawn of social media and will be relevant years after we're all on to the next wave of communication tech. Living separate lives leads to, well, separation. Make sure you have not only tasks in common, but people too. "Make an effort to include your partner's friends and family in some of your activities," Ogolsky suggests.

Are these strategies dead simple? Yes, they are. But with marriage, the trick doesn't appear to be anything complicated or esoteric. It's simply putting in the effort to keep doing the fundamental but incredibly important things over time.

"Relationships are like cars in that you have do certain things to keep them running, especially when your goal is to strengthen and preserve your bond with your partner," Ogolsky commented.

"Persons who use any of these maintenance strategies will not only be more satisfied with and committed to their relationship, they are also likely to continue to love and, yes, even like each other throughout its duration."