It might seem obvious, but if you lift weights, you'll increase your strength. This is helpful not only in the gym, but also in daily life. You need strength in more things than you think you do. Increasing your strength makes everyday living easier. Muscle also burns more calories than fat – even when you're at rest. To burn more calories, you have to build more muscles, which means doing more strength training. Increased strength is useful in all sorts of every day things. From bringing groceries into the house from the car to lifting your kids into and out of the car, increasing your strength will be beneficial.
You'll also get stronger mentally
Not only is strength training good for you physically, but also mentally. Committing to and following a training plan helps you have perseverance. It can be easy to skip a workout when you don't have anything planned, but when you have an upper body workout on your calendar, you're more likely to get that workout done. Achieving fitness goals feels amazing. Endorphins are released after workout which help to make you feel great. Being able to lift heavy things makes you realize that you can do hard things.
Decreases the chance of being injured
Using your body and exercising helps to keep it healthy. Strength training creates stronger tendons and ligaments along with muscles. This in turn creates stronger joints. In addition, you're also more likely to use proper posture because your muscles are strong (and if you're using a balanced strength training program) you can help deal with some existing posture problems. So many people slouch because of sitting in front of a computer at work all week. Strengthening the back muscles and core can help with that.
It's good for your bones
I think just about everyone knows that as you age, you bones become less dense. This is especially an issue for women as their hormones change during and after menopause. Lifting weights can actually help keep your bones from losing their density as you get older. While it won't stop it completely, strength training can definitely make a difference.
This was a huge one for me. A few years ago, the weight room wasn't a place I felt comfortable, so I didn't spend much time there. As a result, I didn't use barbells, I didn't use heavy dumbbells (those things were kept in the weight room of the gym). However once I started getting out of my comfort zone and using the weight room, my confidence went way up. It was definitely scary walking up to a squat rack for the first time, but I'm so glad I did. Now it's not an intimidating thing at all and it feel very comfortable to be in the weight room with all the equipment that I wasn't sure how to use before.
More on strength training
Interested in getting starting with strength training? Check out this post for the basics on the 4 different kinds of strength training. If you're a complete beginner when it comes to lifting weights, it's probably a good idea to hire a personal trainer for a few sessions to make sure your form is good (bad form is an easy way to get injured). If personal training isn't in your budget, most gyms will have an intro to weight lifting class, where you'll get all the basics you need to know (good form, how to use the equipment) to get started in the weight room.