Calculating distance travelled along track in QGIS?

I'm new to GIS.

I have some tracks of people walking from point A to point B that I took using breadcrumbing with Garmin e-trex (set on the Auto track settings). I've loaded the tracks into QGIS and would like to calculate distance travelled along each track (cumulative distance is most important, but distance from trackpoint to trackpoint could also be useful). However, in the Attributes Table I can see only coordinates data, not distance data.

Is there any easy way to calculate distances travelled along tracks in QGIS?