It's not so easy being green, according to a new study which suggests that people's own self-doubt plays a role in how successful they are in supporting environmental issues.

The sense that not matter how much you do for the environment, it's never going to be enough is pervasive among eco-minded people. But the authors of the new study suggest that people's ability to overcome self-doubt will lead to increased environmental stewardship.

It's this never-ending set of doubts of 'Am I doing enough to help the environment?' It turns out that people are very different in how they can respond to these kinds of persistent doubts," said Scott Sonenshein, an associate professor of management at Rice University. "Some people are able to cope with that through building immunity through their self-assets, and other people, unfortunately, fizzle and burn out."

For their study, Sonenshein and his colleagues examined the role of self-evaluations among those who support environmental issues that those evaluations' effects on environmentally supportive behavior.

"Supporting social issues often requires perseverance from individuals who want to make a difference," the authors said in a statement from Rice University. "Our research explains how the mixed self-evaluations of these individuals spring from their interpretation of issue-support challenges."

For their study the authors tested people on their support of environmental issues, then categorized the subjects into three groups. The categorizations were based around the theory that the subjects have positive feelings about their regard for the environment, but negative feelings about their performance on doing enough to protect it.

The researchers defined the three groups as "self-affirmers, who positively channel doubt; self-critics, who respond to doubt with feelings of guilt and hopelessness; and self-equivocators, who become psychologically derailed by doubt."

The research team found that "self-affirmers engaged in the most extensive issue-supportive behavior, which reflects the individuals' strong psychological foundation based on low self-doubts and high self-assets."

However, even among the most dedicated environmentalists, self-doubt plays an important role in their experiences and may be enabling or damaging, depending on the person's personality.

"I would like to see a deeper understanding and appreciation of the difficulty of being an environmentalist," Sonenshein said. "(Environmentalists) have a psychologically very difficult task in front of them in part because of the enormity of the problem that they are solving, and that creates a pretty difficult psychological environment for them to be effective."