Lift light weights to tone up...
Most people think that to tone up those muscles that seem to hang down under your arm and around your chest that you need to lift light weights with high repetitions. Continue doing this and you will not see any RESULTS!!!
To begin with, muscles can not be “untoned”. Muscles are a live active tissue that is firm and they are not affected by gravity. What makes a muscle look untoned, soft and lumpy, is the Fat that is covering that muscle.
To get rid of those bat wings under your arm or to “tone up” your moobs you have to reduce your body fat levels by doing cardiovascular exercise to a level that you are lightly puffing (not a 45 min 
stroll in the park) then you need to make sure you have a significant amount of muscle underneath. This is where weight training comes in. You need to replace, maintain or build your muscles so that when you lose the unwanted fat you look “healthy” not thin and looking like you are starving to death.
For the best results research shows that you will need to lift heavy weights. The weight obviously needs to be relative to your training level and that you are able to lift it between 6 to 15 times. If you are currently doing exercises where you can lift it 20 times or more, your muscles will have no reason to change. If you keep lifting the same weight and never increase it, again your muscle will quite happily stay the same and will not change its ways. Your muscles are lazy little buggers and will only work as much as they need to. Keep increasing your weights and they will have to keep on growing more and making you stronger.
When you work out, aim to do the exercise as many times as you can, don’t restrict your self to a set number. Give it all you have until nothing is left in the tank. If you get up past lifting it 15 times it is time to increase the weight. Lifting it more than 15 times will only teach your muscles muscular endurance and it will not alter the shape of your body.
When it comes to weight training programs just aim to get stronger and your body shape will change. Don’t worry about how many you do or how many times you do it or for how long you do it, leave this up to your Personal Trainer. Just focus on getting STRONGER!!!
Many people go to the gym and use really light weights during their training only to then see them struggle to lift their gear bag and their child into the car. They would have got more of a work out if they stayed at home and did a few squats holding their child or bringing the groceries in from the car. Use your time efficiently, train smarter and to use an old cliché “go hard or go home”.