A personal trainer shares 4 workout mistakes that could block your efforts to build muscle and burn fat for the summer

• The right routine can save you time and effort in the gym.
• If you want a more athletic physique for summer, you should do some full-body exercises a few hours a week.
• Avoid long, exhausting workouts and focus on sustainable changes and good nutrition.

If you want to get in shape for the summer, stop working out like an influencer. Start choosing smarter, time-saving exercises.

That's advice from Ben Foster, founder and head coach of the People's Athletic Club. Many trendy muscle-building workouts are more time-consuming — and more tiring — than necessary, Foster said.

While a lot of the mainstream approach to changing body composition (that is, burning fat and building muscle) come from the pro bodybuilding community, that may not work for everyone.

It's great if working out is your full-time job, but may not be the most efficient for the average person, Foster said.

Smart workout strategies can help you look and feel more athletic for the summer.

"People can do some amazing things in 8-12 weeks," Foster said.

Mistake 1: Setting unrealistic goals

If you're hoping to pack on muscle by July, it's probably too late, especially if you want to get shredded at the same time, according to Foster.

Building muscle is a long process, and trying to rush can lead to injury instead of results.

A beginner can reasonably expect to add a pound or two of muscle per month for the first half a year of training thanks to newbie gains — faster muscle growth when you're first starting out.

The average person can gain about a half pound of muscle every few weeks. You should expect to spend at least three months dedicated to building to see significant changes, Foster said. Optimizing muscle growth also means eating a little extra, so your body fat will likely increase a bit as well.

But you can see significant changes sooner if you mainly want to lose body fat, which can help your existing muscles look more defined.

To burn fat, start with your diet. Focus on eating in a calorie deficit (fewer calories than your body uses for energy) and getting enough protein, Foster said.

Mistake 2: Spending too much time on separate body parts

Trendy workouts often include specific movements to isolate muscles from each angle, Foster said. A common body part workout split, targeting chest and back or biceps and triceps on specific days, can keep in you the gym for hours.

It's much more efficient for most people to focus on full-body workouts, both to build muscle and to improve overall fitness, according to Foster.

"We're working full body because that's what we have — a whole body," Foster said.

He typically divides workout days into push movements (push-ups, bench presses, and shoulder presses) and pull movements (pull-ups, rows) with leg exercises (squats, lunges, deadlifts) throughout.

Compound exercises that use multiple muscles will also burn calories more effectively, if fat loss is a goal.

Mistake 3: Doing too many workouts

More workouts can lead to more muscle-building, but past a certain point, extra sessions prompt smaller and smaller gains, so it may not be the best use of your time.

"There's a significant drop off past 10-12 sets per week per body part," Foster said. "One day is infinitely better than zero, two is exponentially better than one, three is significantly better, but then there's a drop off the additional benefits you'd be getting."

Three workouts a week is a good balance of benefits and time commitment, and Foster said his clients typically follow that routine, with one day each for full-body push exercises, full-body pull exercises, and a little of everything. And none of his client work out six days a week, let alone all seven, since it isn't necessary to see results.

Foster also said that to get the most of your workouts, consider including time for recovery and movement that promotes overall health, like mobility.

"Not every movement should be performed with the purpose of growing the muscle," Foster said. "It can be about building a relationship with your body instead of beating it down."

Mistake 4: Working out for more than an hour

You can see results from working out as little as 30 minutes a day, according to Foster, especially if you're new to exercise.

"A complete beginner can get plenty done," he said.

More experienced athletes can benefit from 45 minutes to an hour in the gym. Beyond that, the extra effort or "junk volume" can lead to diminishing returns and increase the odds that you'll burn out.

"For most folks, if the majority of their days they leave feeling exhausted, it's a recipe for unsustainability and make it difficult to maintain long term," Foster said.