Embodiments of the present disclosure include receiving a sequence of images of a face of a user. A three-dimensional (3D) model of the face is generated and 3D facial points associated with flat facial surfaces are determined. The 3D facial points are projected onto a screen coordinate plane to produce a two-dimensional (2D) facial points. A hue is determined for each pixel associated with each of the 2D facial points in each image. A mean hue value is determined for each image. A spectral representation of a variation in each mean hue value across the sequence of images is determined. A frequency of a main hue is determined based on a largest weight of the variation in each mean hue value. A heart rate of the user is determined based on facial blood circulation according to the frequency of the main hue, and an activity recommendation is displayed.