Even if you weren’t around, chances are still pretty good that you’re familiar with a 1970s ad campaign that showcased a chorus of people singing about how they’d like to buy the world a Coke. (If not, Google it.) That now-iconic commercial went viral before ‘going viral’ was even a thing. So, how did advertisers do it then? And how can you do it now?

Start with emotions. Warm, fuzzy, positive feelings help build rapport and tend to travel faster than anything negative. (Awe and anger works, but why poke the bear and have negativity connected to your brand?) The ad execs from decades ago emphasized a message of love and harmony—during a time when war was top of mind. What can you latch on to that will speak to your audience?

Top it off with a call to action. Offer something helpful that your audience can implement. The commercial’s subtle reminder to have a soda with a band of singing minstrels, coupled with a suggestion that doing so could actually make the world a better place, triggers emotions and a need to pass it on.

When it comes down to it, the ingredients for a viral message haven’t changed all that much, just the mediums for sharing. So, don’t be afraid to take cues from the past as you create your marketing messages in the future.