After a fairly intense workout, Bruce, a relatively new client, looked me right in the eye and said with great intensity, "I do not like doing this kind of thing." Trying not to take his disapproval with my program design personally, I began to offer my usual pep talk about how much progress he'd made and how sometimes workouts needed to challenge.

But all during my little speech he was shaking his head and muttering words of displeasure, so I cut it short. I merely said I looked forward to seeing him the next session, although secretly I wondered if there would be another session.

I'm quite used to those moments when a client voices frustration at herself while performing an exercise that challenges or when I have to deflect mock annoyance when he has to do one more set 10 minutes past the point of fatigue.

And, while I have had several students during a group exercise class complain that they would rather be in a dentist's chair than doing burpees, this client's dissatisfaction with his involvement in exercise and his negation of my words of encouragement made me curious. How can a personal trainer best motivate to achieve repeated success?

Motivation is a tricky thing, tied up tightly among emotions, goals and perceived worth and may not even be known. What motivates one person may have no effect upon another. It may even change from session to session. But it can be highly useful as a training tool during a client's session. If done properly, motivation can propel him to reach new levels and to find that some challenges can be met or exceeded.

You need to lay some groundwork prior to the first working session to delve into the reasons why this person has come to you in the first place. You need to find out as much about her emotional understanding of exercise as you do her physical goals, because motivation is about both the mental and physical. It is as much about what makes them tick as it is about how fast or strong or fit they want to be.

Goals are not merely about toning up but about how better to function during the day. Perhaps a client gives as one goal that she would like to improve her stamina. That's a physical goal, and you would know to gear sessions so that gradually workouts would become more and more strenuous. But unless you find out and tap into why she wants to gain stamina, you are only working with one half of the equation.

If you dig deeper during your initial assessment and probe to find out what in her life she would gain if she had more stamina, you might find out that she wants to be able to play with her young grandchildren. That’s the function she wants to obtain and there's your basis for motivation.

Now, when the work from week two is more demanding than it was in week one, you have a direct link to a goal she wants to achieve, and you can use it to help her get past the doubts she has about staying the course.

This is only one example. Searching for and finding the root of each person's motivation takes some hit-or-miss trying and will require repeated reappraisals. Think about these methods.

Tap into your client's unique goals: Through probing questions, you can find out not only what they want to accomplish but also why. And it's the why that will keep them on track.

Help them to remember progress they've made: Remind them that the previous month, they could only use 8-pound dumbbells, or do 25 squats instead of 30 or anything that tangibly shows marked improvement.

Remind them of what they can do now that they couldn't then. If you learn a client has enrolled in a dance class because he's now more confident in his endurance — that is a jumping-off point for further motivation.

Keep an eye on the future: Once a goal has been met, find a new one and begin the journey again.