I have a ten year old home with construction grade fixtures. In both bathrooms we have the type of shower where you have to pull out the handle to turn the water on and push to close. They are becoming difficult to push and pull so much that while trying to turn the water off my toddler bath I fell onto my tub and did damage to myself because it was so difficult to push in, I lost my balance.

Is this a serious problem?
Do I need a plumber or can I do it myself?

Any tips would be greatly appreciated!

Thank you in advance.