I have been working out with a PT for 6+ years. I lift with him three times a week. I usually do a 10-15 minute cardio warmup first - either stationary bike or stepmill, and 30-45 minutes of cardio afterwards - swim or Zumba class. I also swim 30-60 minutes one other day and try to take a Pilates class every week. I also walk 60 minutes a day - walking is my primary mode of tranportation.
I am a woman, 53 and came to exercise late in life - I lost @ 65 pounds in the first 18 months and have pretty much maintained the loss. The reason PT works for me is that I have the kind of job where you could work til ten o'clock every night...having an appontment to go to the gym makes me go. Knowing that my PT will ask me about what else I have done, including what I ate, how I slept, how I feel, keeps me accountable in other ways.
I lift heavy - for a girl - in fact heavier than almost all of the other women at my gym. However, I am nowhere near the level most of the guys lift at. Although I have made many good friends at the gym, there isn't anyone who I think would be a good lifting partner - I think your partner needs to be lifting in the same range and have similar goals for it to be effective. I do lift by myself if my or my PT's schedule cause me to miss a session with him - but I cannot push myself as hard as he pushes me. I am afraid to lift to failure without a spotter and I wouldn't be comfortable doing things like squats or lunges with the bar without someone watching me. If I do them alone, I use dumbbells, and it just isn't as hard.
I realize that PT is a luxury - that I am paying in part to have someone provide me with positive feedback and reinforcement. I feel really lucky to have found a PT that I like and respect- we have some interests in common (mostly sports) and I enjoy the workouts - but I also love that he has pushed me to the point I'm at. Occasionally, when we are done with a piece of equipment that someone is waiting for, he'll offer to add weight for the guy who is waiting - and the guy will say 'um, no thanks, I have to take some off'...my PT always smiles at me as we walk away and says 'I knew that'...it thrills me how heavy I can lift...and I would never be there without his help.
I give up other things to afford this - I bring my lunch to work every day, and traded some other 'extras' in my budget for this. I also am at a point in my life where I can afford some luxuries....
If you are not going into debt to afford your trainer and you are getting benefit from it, then I think it's normal to want to continue. You could do other things with the money but as long as you aren't digging yourself into a hole, how you choose to spend what you earn is your choice!