Enlightened self-interest is a term used to describe an idealized model where individuals make decisions for the long term (often at some individual expense), that will benefit the individual (and often the group) in the long run. This is the opposite of blind or unenlightened self-interest with a greedier approach that may cause the individual (and the group) to miss out on a valuable long-term benefit.
For example responsible crop rotation may not produce as much of the desired cash crop in the next 10 years as a monoculture based farm, but it will reduce the likelyhood of making the land barren.
Another example is employees willingly taking a pay cut to keep a company alive through a recession, after which the economy is likely to rebound and everybody will reap the benefit.
This is often used as an argument for education rather than government regulation, the idea being that if people are convinced that conservation or resources/whatever is a good idea in the long run, they won't need to be forced to comply, because they will choose to do so out of enlightened self-interest.