"If you need a spotter and are using a spotter, they should be paying attention," Callahan said. "Especially if you're not familiar with the equipment."
Carey suggests asking a gym staffer what machines or exercises might require a spotter.
Pump one, two, three... ten. And rest! But for how long?
Feeling that muscle burn during strength training is an important way to know that you are working, but improperly timing rests between sets can sabotage your exercise session.
Too long and you've lost some of the aerobic benefits. Too short and your muscles haven't fully recovered.
But how much you need to rest also depends on your exercise program, Carey pointed out. For building muscle structure and increasing bone density using lighter weights, the rests between sets should be short. But heavy duty power lifting takes so much energy that the body might need anywhere from 30 seconds to three minutes of rest in order to recover.
Still, if a long rest between exercise sets keeps you heading to the gym, Callahan said it can be worth it.
"If the only way you're going to do it is to rest, that's better than not doing it at all."
For some, even a trip to the gym can bring out an inner stylista. While looking nice while working out can be a boost, it's important to keep clothes comfortable and practical, experts say.
"Think simple at the gym," Carey said. "You're there to work out and make yourself healthier."
Shoes can be a problem. Flip flops or other kinds of street shoes are a no-go on machines or on the gym floor as they can cause slipping or pain due to poor support.
Wearing appropriate, comfortable sneakers can aid balance and form. Or, for exercises requiring more functional movements -- yoga or weight lifting, for example -- a flatter, more natural foot is better and no shoes or shoes with a smaller arch are best.
Appropriate clothing can take many forms. The form it should not take is baggy or overly accessorized.
Baggy shirts or pants and belts or other jewelry can get caught on equipment. They may also make it difficult to see what the body is doing.
"People try to get too trendy," Carey said. "But that can distract you ... and risk a movement you might be doing."
Weekend warrior sounds like a glamorous title to be carried with pride but it comes with caveats.
"You kind of get all the pain without the gain," Callahan said.
Weekend warrior refers to anyone who gets the bulk of their physical activity during a few days of the week, usually on the weekends, often because of work or family-related time constraints.
"If you only work out hard two days a week and on consecutive days, the risk of injury goes up," Callahan said. "Your muscles aren't prepared and you're likely to overdo it."
A week's worth of rest between exercising keeps your muscles from adapting to exertion and getting stronger, decreasing the overall effectiveness of the exercise.
And based on past studies he conducted, Franklin said that, particularly among adults in their 50s and older, people who had a poor attendance record at a gym -- averaging twice monthly -- were more likely to have serious health problems and even death due to exertion.
Franklin noted that, while his study was conducted on heart patients, the data is one example of how sporadic exercise can be harmful.