Unfortunately for some personal trainers, and their over 40 clients, the phrase 'No pain, no gain' really means 'you should feel some pain'. Ordinarily mild discomfort is to be expected when working out, especially for those just launching a new fitness routine. On the other hand pain is a natural warning sign. You are advised to pay close attention to it.

A properly designed workout routine should test you, but shouldn't damage you. As muscles get used, especially somewhat beyond their usual range, lactic acid, micro-tears and other physiological changes occur that result in muscles being built up stronger than before.

However if you are experiencing back pain, neck aches, knee joint soreness and other symptoms - and since your over 40 you will - you should consult with an expert. It could be that your technique may be wrong, you may be trying to conquer too much, too soon, or you may have a medical problem that should be addressed. Next to bad warm-ups or overdoing it, incorrect technique is the leading cause of injury.

The secret is to work up to any vigorous routine slowly. The tricky part is that 'slowly' will vary from person to person, depending on age, experience, prior exercise routines and overall fitness. Importantly always remember to get muscles warm and limber before cranking it up. Far and away a majority of strains and rips result from being too cold and not stretching, or extending your workout routine for more than you're ready for.

A proper warm-up should take a minimum of 15 minutes and include very gentle jogging or jumping jacks to get the cardio and lung systems engaged. Warm-ups should also include some slow, gradual stretching to get joints lubricated and muscles relaxed and gently lengthened. Warm-ups that are too short can easily lead to stretched or torn cartilage, an injury that takes a long time to heal.

Stay away from inexperienced personal trainers, or so-called 'friends' embarrassing you into fitness routines that stretch your beyond your comfort zone.

Also don't be fooled into believing you have to get out and run five miles two weeks after an injury, surgery or other debilitating condition. The very nature of physical therapy and exercise sometimes require that you work against discomfort, but you simply don't need to over do the process your first day out.

Part of the satisfaction of over 40 enthusiasts is being committed to fitness and wanting to push him or herself to achieve excellence. But an attitude that leads to overdoing it is counter-productive to your goal. At this time in life your goal is working to improve or maximize health and overall body tone and strength - not proving you are 'mentally tough'.

One of the best investments an over 40 fitness enthusiast can make is to hire a personal trainer. At a minimum before beginning any new routine that involves unfamiliar activities be sure to get the proper guidance from an expert. If you don't know how to use a station at the weight machine correctly, never be embarrassed to ask. The are countless clients in the local gym that are gunning for a painful and unsuccessful work-out experience all because they simply will not ask for help.

Awareness of your spatial environment while you go through your routine is important. It's easy to get into a rhythm, get concentrated on your workout and end up crashing into a wall or a nearby person. Jogging in the street especially requires that you pay attention to the surface you run on and the people and cars around you. Running shoes will not prevent accidents, only awareness and good reflexes can help.

So being is a great idea. Just remember to stay within your comfort zone as you gradually expand it. The foremost reason people give up on workouts is injuries produced by working beyond their capacity. That makes working out no longer fun. Building up, while you build out, to increase your ability to do more, faster will keep you going for years to come.