Honestly, I still had to practically stand on the clutch with mine!
I'd teach someone to drive it and say, "now push down on the clutch". They they would heave and struggle, then eventually succeed and look victorious. I'd say, "well done, it is now half way down! But that's all you need for now!"
EDIT: To fully explain: It has a two-stage clutch. You half-press it and it disconnects the wheels from the engine. If you fully depress it all the way to the floor, it additionally disconnects the power-take-off shaft (PTO) from the engine. The PTO shaft is a spindle on the back of the tractor which drives things like your flail mower, wood chipper, etc.
EDIT 2: Edit 1 was for the general audience, not the parent commenter ;-)
> The PTO shaft is a spindle on the back of the tractor which drives things like your flail mower, wood chipper, etc.
... and kills/maims anyone with lose clothing trying to step over it!
Why was the clutch so heavy? Did it serve some purpose or was it just due to the limitations of the technology at the time?
I have certainly driven cars with lighter and heavier clutches (I live in EU, automatics weren't popular until recently and are still far from ubiquitous) but I couldn't tell you why every model just doesn't get a light clutch for comfort. A diesel Subaru I drove had a particularly heavy clutch as I recall, so at stop lights I would pop into neutral instead of holding the clutch down for an extended period.