Burning calories on exercise machines - not worn out as i used to be?

[Folin]

I burn 150 cal on the cross trainer,
100 cal on the stepper and 100 on bike.

but for some reason i dont get as knackered as i used, and i dont sweat anymore.

so am i burning less calories?

even though machines are saying 100 cal and over on each machine

i dont go jogging, as i dont really like going jogging on my own.

so i just do the machine exercise at home, and sometimes aerobics at home using dvd.

will i be still able to lose weight? even though am not that tired? do i have to increase my time on the machine?

thanks in advance all
i excercise 4x a week