1) Get to the gym. Nowadays, many people own exercise equipment at home. I.e. treadmills, Bo-flex etc. But your home is where people like to relax. Going to a gym will put you in the mindset of training. Not only that, seeing others working out will get you motivated.
2) Change up your rep and set schemes. After doing the same routine for an extended period of time, your body tends to get used to it. And learns how to do it more efficiently. Switching up your reps and set scheme will keep your body stimulated and on the continuous path of growth. Not to mention the fact that you won't get bored with your workouts.
3) Take pictures and write logs of your progress. You won’t know where you’re going unless you know where you've been. At times it is very difficult for us to notice our own achievements. By taking pictures of your progress you're able to see how much your body has changed and that will keep you motivated to stick with it.
4) Leave your Ego at the door. If the weight is clearly too heavy for you it is ok to grab one that's lighter. No one is going to think less of you if you do. Trying to lift more than your body can handle, may eventually lead to injuries. Injuries mean you won't be training for some time and that will hinder your progress. Practice safe training.
5) Remind yourself of your goals daily and share them with others. Motivation is like eating and taking a bath. If you don't do them each day, you'll starve to death and smell bad. Post pictures of things that motivated you to get started in the first place everywhere. Seeing them will reignite your passion. Share your goals with friends and family members. They will help keep you accountable.