I just changed my Clutch on my Truck and I'm having some problems can anyone help?

So last week I was trying to get my car out the garage but then I couldn't change the gear. I was finally able to take the car to a mechanic and he changed the clutch but when I tried it out it's really hard to change the gear (I had to use a lot of force) and when I asked the mechanic why it's like that he said it normal and that in about a week it will be better / smoother but I don't find that convincing.
So can anyone help please!
BTW It's a 2000 Ford Ranger

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