I find that (in general - so don't stone me) most SEs fall into one of two fairly common camps - those that lean more towards the technology side of things... and those that lean more towards the sales process side. There are many homes for each - but in my particular environment - we really need SEs who are more "sales-savy". Our technology is not overly complex and we can teach just about anyone our solution (we prove that with our customers every day....buh dum bum) - but we can't train SEs to have strong "presence" at the whiteboard, or give them intellectual curiosity - or strong listening skills - or the ability to vary their communication styles based on audience. At least not in 90 days. So we tend to seek out those candidates who are more attracted to the sales process - the ones that have, and want to continue to develop skills and abilities that close sales - like their AE counterparts.
Now, I actually said all of that to ask you fine folks this.... There are lots of threads asking what "technical" skills should an SE develop next in order to be more marketable/successful. My counterpart to that question is - what "sales-oriented" training (or courses or books) have SE's found extremely useful in the field. Not just the stuff you thought was OK-ish.
I know a few SEs that think Sandler is great. Others love Demo2Win. People tell me about story telling seminars. And I'm sure all of these contenders offer valuable insights, but I'm curious to ask the SE practitioners out in the field which sales-oriented trainings they have found most valuable in the real world. The stuff that actually got you to change what you were previously doing and has worked out really well for you.
(Code of Conduct note: we don't need to throw rocks at any offerings that you considered below par)