Set a time the night before you want to work out. Then dedicate your workout to someone/something close to you. (Ex. Someone physically unable to workout) It'll give you what you need to show up and work harder!
It's all about your mindset. If you sit around thinking "I hate working out" you won't be able to get through a workout. Tell yourself "I'm going to feel so great after this workout" and it'll go a LOT better.
Take before/after pictures. Once you start losing weight you will see the difference and nothing is as good of motivation as seeing results. Also try doing fun exercises and activities, or even stepping up simple everyday tasks. For me music (especially up-beat music) is a great motivator.