I hate going to the gym. It's hard work, I get the whole 'reward relationship' thing but why can't it be fun. If it's fun it's not working you will be told. Well, to get in to the habit of going to the gym to be able to do punishing workouts you have to make the gym a place you want to go. Otherwise, and stop me if this sounds familiar, you'll go a few times and hate it and then stop going.
So, here's my tip: Just go to the gym three times a week for 45 minutes for 4 weeks. When you get there, forget about plans, just use what you want to use. Go where you want to go. Stay active and get sweaty but let yourself play and enjoy the environment. When you've got used to going you can then start to kick your ass in the knowledge that you like going and so will be more motivated to tough it out through the 'I hate the gym' phase before the rewards kick in.
Trust me, I've been there. No pain, no gain maybe right, but equally and even more right is: no train, no pain, no gain.
You've got to be in it to win it...the gym that is! So get down to the gym and have some fun. bet you never heard that before!