When you're in between series: William Shatner for Promise (1974)

 There was a time when Promise margarine, at the time packaged by Lever Brothers, was touted as beneficial for lowering cholesterol.

From 1974, here's William Shatner in New Jersey.

This was included in a compilation of short-lived series from 1975, since this ad was still circulating at the time. Shatner would bomb with Barbary Coast in '75.