Mouse said:I would say and write 'I was sat on the chair' which is passive.
Gah! You do what I did! I'd grown up hearing people say "I was sat...", and John Jarrold was the one who pointed out that it's not grammatical. It's either "I was sitting", "I sat", "I am sitting", "I will/might be sitting", or "I had/have been sitting", etc. "Sat" = past tense; "sitting" = continuous (present participle).
And again, "affect" is primarily a verb, whilst "effect" is primarily a noun: "The accident had a profound effect on him -- affected him more than people realise."
And don't be too quick to dismiss "I was sitting". It's a valid form of expressing the time the character's action takes place; i.e., "She was going to the cinema" implies that she was going but whether or not she got there is in doubt at the present time until further clarification -- maybe she got waylaid. "She went to the cinema" implies that the lady did get there. Different, no? Both are relevant to what you're trying to say.
Whereas passive voice is bad when used in the form of lengthening your prose unnecessarily or confusing the reader into wondering who's doing what. Consider:
Jim was always tortured by Bill.
Bill always tortured Jim.
Our car was red and shiny, and we liked to speed up the road in it.
We liked to speed up the road in our shiny red car.
Of course, passive can be good to emphasise a point or heighten tension:
"We were being pursued" -- Here, the pursuers are unnamed, adding tension, rather than "The men/women/cyborgs/goats pursued us".
"It was a look I dreaded..." -- In some circumstances, this can sound better than "I dreaded the look", because putting the "a look I dreaded" after the "was" makes the reader unconsciously drawn to it -- the point of tension, the important thing you want emphasised -- rather than drawn to the "I" as in the second example. I hope that sounds clear...
Oh, and yes, Mouse, it would have been "affect" in the title, because you could substitute it with the verb "to alter".
Hope this helps!