1. A method for processing motion-related sensor data for health application, the method comprising: receiving motion-related signals from motion sensors located on different subjects, wherein the motion sensors comprise at least one accelerometer and at least one gyroscope integrated within a smartphone; processing the received motion-related signals on a frame-by-frame basis to detect distinct short-duration exercise motions performed by the subjects, the distinct short-duration exercise motions including arm motions, leg motions and full body motions, each frame representing a predefined time interval shorter than the total duration of a distinct short-duration exercise motion; for each frame, performing a plurality of signal transformations to extract features for activity classification; for each frame, performing hierarchical decision making using feature subsets for a plurality of different categories of short-duration exercise motions to classify a number of motion categories of the plurality of different categories of short-duration exercise motions; for each frame, classifying a detected distinct short-duration exercise motion into one of the number of motion categories; for each frame, estimating performance parameters of the detected distinct short-duration exercise motion, wherein the performance parameters define the performance of the detected distinct short-duration exercise motion in the frame; and creating a picture-based mind-body and reward-based game that is associated to a particular subject of the different subjects, wherein the picture-based mind-body and reward-based game includes at least one of the distinct short-duration exercise motions to be performed using the smartphone to play the picture-based mind-body and reward-based game.