Remember to consider the consquences of your actions.

Building a platform in the Gulf, for instance, might cause an overpopulation of some species and the decline of others. Redoing the water distribution for the planet might well cause deserts to bloom, and that would cause displacements elsewhere. End war and you might affect humanity's idealism.

Unless "cannot fail" includes the consequences. But then, you'd take away humanity's hope for the future. If your action could NOT fail in ANY way, EVER, then whatever you'd do, however small, would positiviely affect everything.

If there is no chance of failure in human affairs, there is no progress, no learning.

Just consider the consequences of your decision.