Lunges are one of those Necessary Evils, I think
And, my trainer L-O-V-E-S them. So I end up doing many.
When I first started working out with him, I couldn't do many - maybe a couple reps of 15 each. And they burrrnnn. It has taken some time for the burn to be less while I am doing them.
I agree - if you are hurting while you are doing them, ask someone to make sure your form is correct. If you are hurting the day after, stretching helps quite a bit, or doing cardio on alternate days. I do lunges one day and spin the next.
The good thing about lunges and squats are that they get to that fat spot on your inner thighs and tighten it up nicely. No other exercise really gets at that spot so well.
We also hike quite a bit, on trails that have a high elevation gain and loss, and doing lunges makes it that much more easier.
Good luck