If it is the message, IMHO you do not have to worry about making "the visuals fresh and engaging" because it would appear that your primary desire is to deliver compelling stories and/or ad-libbing. If it were me I'd be concerned about distracting the viewer/listener from the message by incorporating "fresh and engaging" visuals.
That being said: change positions - standing, sitting comfortably, leaning into, or away from, the camera, shifting gears with the pacing of your delivery, using props, support visual materials you have at hand to hold up and show, animated facial expressions, actually stopping and taking a moment to sip from a cup or glass.
Invest your personality into it - something a bit more compelling than, say the late Mr. Rogers or Captain Kangaroo. But perhaps less manic than PeeWee Herman. :-)
Of course, ever-changing backgrounds ranging from the hypno-cycle thingy, to Outer Limits effects, lava lamp style backgrounds, etc. if they happen to support your material/content might be in order.
I'd go for the personality and personal delivery more than a distracting background environment, however. Especially if you intend to go to the web with this, making that ever-changing background a serious challenge to good compression schemes.
A static, high-quality background, over-the-shoulder and high-tech background environment might come off professional, but then your message, again IMHO, would have to meet up to the visual expectations you've established and you probably could not afford to come off too casual.
