What motivates you to walk into the gym and finish a workout? Is it your health? Is it your family? Whatever it is that makes you want to be a better person, hold on to it. If you have powerful reasons for enacting a life change, it will be harder to fall back into your old habits.
As you finish today's workout, take a look back at your workout log. How have your weights increased? How do you feel after your workouts? Are things getting easier? Do you feel more confident? Taking a moment to look at where you've been can help make the future look that much brighter.