Enviromentalism And Social Justice, But Why?

I'm all for recycling, reusing, using less energy, buying fair trade products, trying to drive less/cycling, and whatever else. I've noticed that a lot of other people are, too. These things are great. The problems behind them are the motives. It all seems very trendy. It has a huge following from people my age, which of course will make it seem cool. Apparently, anything large masses of college-aged, twenty-somethings do is trendy, or so I perceive. Being trendy and following the crowd are not things I want to base my actions and lifestyle from. I'm not trying to simply go against the crowd, either. Ironically, that's pretty trendy, too.

I want to do these things for these reasons: to use wisely and gratefully what I've been given, and to live simply, so that others may simply live. Or at least that's what I should want. I've been given so much, parents that support me, certain freedoms others don't have, healthcare, good health, education, clean water, breath...the list can go on for ever. All great things, but I should live in a way that reflects gratitude and compassion for others, because I am grateful and genuinely care for everyone else, not because it's the thing to do.

Caring about the environment and taking action on social justice problems are very good and necessary things, but why are you doing them?