Making smart health decisions involves gathering good information. Unfortunately, today's diet and exercise world are filled with unreliable sources pedaling inaccurate information to further a specific agenda (gym memberships, personal training packages or supplements). When you get information from unreliable sources, you will make bad decisions.
1. People That Look Good. The people you see at the gym who look good aren't the best people to get advice from. Yes, what they're doing is working for them but it won't necessarily work for you. A huge part of how quickly we can get into shape (losing weight, putting on muscle) is written into our genetic code. A bodybuilder might know what worked for him, but trying to adopt his plan might not be the best one for you.
2. Fitness Magazines. Magazines can be the worst places to get exercise or diet advice. Most (not all) magazines are sponsored by big supplement companies who are trying to sell products that don't necessarily work. It isn't clear how much creative freedom the writers have, but the supplement companies probably wouldn't be too happy with an article criticizing them right next to their full page ad. If you're going to read fitness magazines, find a reputable one that isn't afraid of upsetting anyone.
3. Personal Trainers. Depending on what educational background and certifications a personal trainer has, they might not be the best person to get exercise information from. Certifications sometimes only require a simple online test that anyone can pass. There are hundreds of certifications a personal trainer can choose from but few actually translate into real knowledge. You should also check to see if they have a degree in a relevant field.
4. Sales People. Some people make a living by selling products which claim to improve your health. If you're going to use supplements, do your research before asking the sales person for advice. They are trained to sell you pills and aren't going to tell you if a product is ineffective. They might say, "That one doesn't work, but this more expensive one does."
5. The Internet. The internet is another place you need to be careful of (except for this site - shameless plug). Like other bad places to get information from, the internet is full of people trying to make a quick buck off of you. Avoid places that push a particular product too hard.
The Bottom Line
Finding good sources of health information is one of the first steps you can take in improving your overall health. You can only start moving in the right direction when you are steered by solid information.