Well, for me the decision was more about focusing on my lack of strength training. Cardio I do plenty of, with all the running and spin classes. But, strength training I was completely lost as to what to do and to do it on my own without a class or dvd to tell me what to do can be boring. I often find my mind wandering and thinking about the workout being over if I don't have someone constantly telling me which exercise is next. But, after my sessions with the trainer I find it easier to focus on which exercises I want to do and do them properly.
If you go enter into personal training with a goal in mind a personal trainer is a great way to go if you can spare the extra cash. You'll get the someone to advise you on exercises specific to you. Which for me is awesome, I do tons of leg stuff to keep my legs strong and to help with getting them toned. Having the experience of working with a trainer definitely makes me think more about how I do certain exercises, especially when weight training and making sure I'm lifting properly. I've gone lifting 8lbs to 15lbs and can't wait until I'm using those 20lb weights. I definitely started to see more definition in my arms after working with my trainer and a few more inches off my waist. Just to give you an idea of where I started from about 4 years I was a size 24, I am now between a size 12/10. Getting down to a size 8 is my goal!
Here is a great guide I was given (the exercises are totally up to you); I usually run at least 3 miles before going through this routine (which makes for an hour long work out) and pick one or two of the variations for each body part:
Start with a chest exercise, back, legs, abs in that order 1st; then arms, shoulders, legs abs again.
Ex. of Chest Exercises:
Pushups (always my favorite)
Push up position - tap shoulders
Ex. of Back Exercises:
Back rows: there are lots of variations of this exercise. You can always add reverse lunges to it as well (sometimes I add squats because those are my favorite) or do this is stork position.
Ex. of core/abs workouts:
Planks!!!! (you really can never do enough planks, there are tons of different versions as well)
Extended V Sit ups
Bicycles (frontwards and backwards)
Ex. of Leg Exercises:
Walking lunges (do these with weights by your side or do an over head press for added difficulty)
Wall sits (these are much more fun when you march in place while wall sitting)
Side lunges (definintely hold weights while doing this too, even add in a curl or press as you come up)
Ex. of Arm Exercises:
Curls with lunges or squats are great - you can also do them while wall sitting
Tricep Kickbacks (one of my favorites, especially in stork position meaning your only standing on one leg while performing the exercise. This can also be used when doing the rows)
Side raises/front raises
Shoulder press - you can add that to curtsey squats or lunges as well...
Go through strength exercises 2x each 10-12x
What are some of your favorite exercises?