One size doesn't fit all

A good few years ago I went in for all sorts of training courses, some of them suggested and paid for by my employer at the time. In particular, I recall that two warring departments were frogmarched onto a course on effective communication facilitated by an energetic lady who seemed to think that we were all a menace to society in general. 'Say something positive to the person next to you,' she challenged.  I was first in line and all eyes were upon me.  Now it just so happened that the person sitting next to me was a colleague with whom I'd had rather a nasty spat the week before. Some very bitter words had been exchanged and we were both convinced that a) we were in the right and b) the other person was a thoroughly nasty piece of goods.  What could I say to her that would be acceptable?  I still remember the panic that swamped me, the overwhelming desire to get up and run.  But there was no escape.  In the end I think I admired the blouse she was wearing. The facilitator's chilly eye fell on me and I knew she was classifying me as "not a team player." 
And that's sometimes the trouble with these kind of courses.  Some facilitators, not all I hasten to add, have very definite ideas on how one should behave in certain circumstances.  One size doesn't fit all, though, as I learned to my cost many moons ago.  A friend of mine dragged me to a course on self-assertiveness which she reckoned I badly needed because she said I was inclined to get lumbered with extra work. 'Learn when to say no,' said the lady holding the course. It all sounded easy so I decided to put what I'd learned into practice next time my boss came and asked if I could do something over and above my workload.  I can't remember what he wanted done now, but the details don't matter.  I told him politely and regretfully that I was simply too busy.  He accepted this immediately and I felt the first flush of triumph at having taken a stand.  I should have done this long ago, I told myself.  And then came the downside.  My boss never again asked me to take on any extra work and when a promotion to team leader came up, I was bypassed, being too busy to be given extra duties, no doubt.
Lesson learned for me is that what works in one situation is by no means sure of success in another.  At some stage I decided to use my gut feeling and a bit of commonsense and this has carried me through the rest of my career without too many blips.  Maybe that's the secret, maybe we shouldn't try to be what we are patently not. Recognizing our weaknesses is a major step on the way to coping with them but we shouldn't overdo it. Should I have accepted more work from my boss all those years ago and maybe been promoted to team leader?  I really don't know and when I think about it now, it doesn't really matter, does it?