If you feel you don't have the motivation to train or don't even know if you are doing your workouts correctly, you may want to invest in a personal trainer.
However, before jumping on the next fitness trainer available in your neighborhood gym, you should look out for certain qualities in him/her before appointing him.
First of all, don't be afraid to ask him questions.
Ask him about his education, experience and what certificates (such as NSCA and CSCS) he has.
Inquire if he can give any references of clients he has worked with before (and then, actually talk to them to get their feedbacks about him).
You should know if he has any special area of expertise such as muscle gain, sports fitness and rehabilitation.
Once you appoint him, tell him about any past injury you suffered, your overall medical history and any special needs of yours, so that he can work your fitness plan keeping these in mind.
Your personal fitness trainer should be fully committed towards you and push you hard in a safe way, keeping you motivated at all times.
He should be knowledgeable in various workouts and fitness techniques.
Since he would be influencing you in a major way, he should himself be disciplined about his timings and not bring any distractions like talking on the phone in the middle of a workout session or even conversing a lot with you, more so as he would most probably work on an hourly rate.
He should be able to tell you the right nutrition complimenting your workout and your fitness goals.
A right personal fitness trainer could really help you in achieving your weight training objectives effectively and in a faster way.
Forgot to add above, don't get upset if he sometimes gives you some 'hard love'.
It only means you have made the right choice!