There is abundance of lost mechanical energy that can be harvested and recycled from our living environment. Here we developed a pendulum motion based triboelectric nanogenerator (TENG) that sustains its motion with low maintenance providing multiple output peaks from a tiny-scale single mechanical triggering. The triboelectric effect of our device is enhanced by the surface structure of the PDMS that is composed of micro roughness with nanowires. We demonstrated lighting up a commercial LED light bulb by harvesting lost mechanical energy of the pendulum oscillation of a wall clock. Our approach can be a promising platform of developing a sustainable, low maintenance system to harvest lost mechanical energy.