I'll do it at some point.

I'll answer this message later.

I could try this sometime.

For most people, all of these thoughts have the same result. The thing in question likely never gets done - or if it does, it's only after remaining undone for a long time and causing a considerable amount of stress. Leaving the "when" ambiguous means that there isn't anything that would propel you into action.

What kinds of thoughts would help avoid this problem? This is the domain of Trigger Action Planning/Plans or TAP(s), which is our topic of discussion for Easter Sunday. See you there!