There is nothing worse than training so hard and achieving great results, only to have it all fade away due to a lack of motivation.
Now that the weather has gotten warmer, it’s nice and sunny outside and the thought of chilling out at home or having a drink at a BBQ can become more appealing than the thought of exercising. What needs to be kept in the back of your mind is that the hardest part of exercising in these conditions is getting yourself up and into it, you will never regret a workout once it has started, never.
Maybe there are more issues, family problems, relationship issues, your training buddy bailed on you, the list goes on. There is nobody on Earth that doesn't have those problems at some point in their life. It's whether you can push through those tough times and keep training that defines you, with many, these are the times that produce some of the best workouts. In that time, you have the opportunity to put whatever is going on at home behind you and focus on your immediate goal of smashing the session you have entered.
No one can give you that motivation; it needs to come from you. Others (such as Personal Trainers) can try to help you along by developing new workouts, contacting and encouraging you, but if you can't find the fire yourself, no one else will be able to feed it and make it burn. You need to find what works for you, whether it's closing your eyes and visualizing your goals or even finding that really great song or motivational video clip that gets you going!
The bottom line is, don't let external factors (weather, partners, family etc) be the reason you stop chasing your goals. Be strong enough to find the time and chase them down as hard as you can! Don't let the little things stop you from reaching your potential!