I love cardio exercises but my nutritionist told me to lift weight because I was losing too much muscle. It took me a while to like it and to adjust (for instance, I couldn't use those work out machines -too painful on my back and arms-, instead I now use dumbbells and I enjoy it much better).
Make sure your technique is correct too. It is too easy to hyperextend your lower back, or work your shoulders when you should be doing your chest. Look up Google and Youtube for instructional videos and advice.
Those machines are terrible for you anyway. You get really "strong" but then when you have to actually lift something in real life you hurt yourself because you weren't working out all those little stabilizing muscles and such. Dumbbells are the best followed by barbell. This is personal opinion not meant to be construed as fact, but I'd be deeply surprised if most serious lifters didn't agree.
I used to jog until I realized not jogging was more fun in the short run. Help me.
Trainers are bloody good if you can afford them, knowing that every appointment you miss costs you money is a good motivator to get off your arse and do what you know you have to
Make a rule, if you didn't jog you don't get to do X (where X is something you'd normally do): go out with friends, have a beer, eat desert, whack off, use the internet, whatever, find the one that missing pisses you off enough that you'll go.
The trainer is a good idea too, if you can afford it, that is fine, the above is free.
EDIT: Obviously to michaelleung.