If you're a stranger to PT here's some advice, they love proactive people.
1. Go in with a list of aims, things you need to be able to do earlier than other things. Run through the list so you have something to tick off as the weeks go by - mark your achievements.
2. ALWAYS take painkillers an hour before you go, they will be manipulating you, it will hurt.
3. If it hurts overly, and you have taken painkillers then you are going at it too fast and need to slow it down, and you have to be able to discuss this with your PT honestly. Don't be pushed into doing anything thats going to leave you in pain for hours and days.
4. Some days are better than others, so go with it if it's a bad day and try again the next day. That also applies to mornings, afternoons and evenings.
5. Most PTs are younger than you and may have no idea what you could do beforehand, so tell them. Control the session yourself, don't be pushed too far.
6. Do your PT every day, if only part of it, it really helps to see how you are improving. Write down your exercises, you will forget.
7. Remember baby steps to start with, your recovery is usually twice as long as your immobility, and can be a fair bit longer.
8. PT in water is excellent, doesn't hurt so much, you achieve far more. You are very tired afterwards!