Push-ups on your knees or standing, pushing up from a wall, are a great place to start.

Push-ups on your knees or standing, pushing up from a wall, are a great place to start.

When you're just getting back into exercise—or maybe this is pretty much the first time you've ever worked out regularly—one of the toughest things is just knowing where to start. What exercises should you do? How often? How do you know if you're doing them right? What if you get hurt? It's enough to make you give up and just stay on the couch.

That's one of the main reasons so many people choose a goal.  A goal gives you both a place to start and something to aim for. It also gives you a WAY to get where you want to go, since for many fitness goals you can find zillions of programs and plans designed to help you reach that goal. Here are some of the most popular goals:

·        Start walking regularly.

·        Run 1 mile.

·        Run a 5-kilometer (3.1 miles) race.

·        Do a triathlon (a race that includes a swim, a bike, and a run)

·        Run a 10-kilometer (6.2 miles) race.

·        Run a half-marathon (13.1 miles).

·        Run a marathon (26.2 miles).

These are all good goals, and there are many, many others. The trick, then, is choosing the one that's a good fit for you, based on your fitness level, any restrictions, what you enjoy doing (and what you don't), time, money and more. The most important aspect of choosing any goal is that it's realistic, says Chris Chinn, co-founder of Sweat City Fitness, a boot camp and athletic training business based in Los Angeles. "You need to evaluate where you are; if you're out-of-shape you can't say, 'I'll do 100 push-ups by the end of the month.'"

Chinn adds that any goal you choose also needs to be specific: "Your goal should be something quantifiable, something that you can measure. And you don't want to just set specific goals, but set multiple goals so that you can address all the body part areas. " So perhaps you have a weight-loss goal as well as one for upper-body strength and one for lower-body strength. "For your upper body you might see how many push-ups you can do in a minute" and aim to increase that gradually over time, suggests Chinn. "For lower body, you could decides to do X number of squats in a minute. For your core it might be how long you stay in a Plank for." For cardio (aerobic conditioning), you could tell yourself that you want to be able to run one mile in a certain amount of time. "That measures stamina versus body part," explains Chinn. "It's really addressing what's important to you."

What's nice, too, about multiple goals is that if you've stalled on one—maybe the pounds aren't coming off as quickly as you'd hoped, or doing more push-ups in one minute just doesn't seem to be happening—you are likely to see progress on another goal, which is very motivating.

As mentioned above, it's also important to set realistic goals that reflect where you're at with your fitness. So your first attempts at Plank may be doing them on your knees. That's absolutely fine. "For the average beginner a  good place is to start on knees and hands and hold that for 25 to 30 seconds," suggests Chinn.  "A good way to work up is to add 10 seconds every week. Once you get up to holding Plank for a minute, change it do the move off your knees and work your way up to 1 or 1 1/2 minutes off your knees." For push-ups, do as many as you can "until you have to stop, or you faceplant," Chinn says, or simply do 10 push-ups, then rest for 10 seconds, then repeat, alternating push-ups and recovery, for one minute.

You should also consider goals that don't seem to be about workouts but have everything to do with keeping you motivated and seeing results. If you have trouble getting to sleep before watching Jimmy Fallon, for instance, make a commitment to get one or two hours of extra shut-eye the night before, say, three of your weekly workouts. Getting more and better-quality shut-eye will have a huge impact on your energy level. Similarly, if you don't like to drink water, make getting two more glasses of water (watered-down juice or seltzer/soda are fine too) a day a priority.  Or maybe your only goal is to work out for 10 minutes two days this week--that's it. That's a great first goal, in fact.

Just as it's important to set more than one fitness goal, you should also set both long- and short-term goals, says Chinn. "You're going to have bad days and good days. Achieving shorter-term goals offers motivation to keep you going at those midway checkpoints at a week, two weeks, or a month. It will help you keep yourself on track and motivated."

What's most important about any goal you set is that it's meaningful to you and that it's something you can achieve. So if your goal is to do one push-up a day or eat one more veggie a day for a month, that's a great place to start.

What's your fitness goal? Which ones have you achieved already?