Well I don't need to tell you that it doesn't come for free, but it really depends on what your goals are; so be more specific what are you looking to do right now?
I have a lot of muscle but I'm just wanting to slim down and lose fat
When I started I had the same goal and in terms of motivation I found that it comes from actually doing the thing you want to do. If you get up and push yourself hard you feel proud afterwards and just enjoy the rest of your day. The next day you repeat and you feel better and so on and so forth until one day you're working out and you realise you "Enjoy the burn." Because you're proud of all the hard work you've done, you've earned it and no one can take it away.
I hope this helps, please tell me if it does, and always remember when something becomes easy step it up to keep pushing and get better.
Keep mixing it up with your workouts. If you go to the gym try going at a different time. Learn a new exercise. Do a gym class. Get a new gym costume.
Don't quit suffer now and live the rest of your life as a champion......
Every accomplishment start with the decision to try....