Believe me, whatever you're doing, you can do more. And no, you won't overtrain; you'll just advance faster when you push your limits. I used to think squatting 405 pounds for 10 reps was great. Now I can do 405 for 25 reps and it's okay, but I know I'm going to get up to 35 reps. Don't be afraid of more weight and more sets; just push a little more each and every workout (even adding 2.5 pounds is great). The greatest athletes in the world have done things that everyone thinks are crazy, but these are the same people breaking world records. Trust me, you can always do more. Train hard, train harder!
The American College of Sports Medicine recommends that resistance training should be progressive in nature (for example, follow the principle of progressive overload - see below for an explanation), individualized, and provide a stimulus to all the major muscle groups (chest, back, shoulders, arms, abdominals, and legs). They recommend that beginners do one set of eight to 10 exercises for the major muscle groups, eight to 12 repetitions (reps) to fatigue, two to three days per week (multiple-set regimens may provide greater benefits if time allows). For older and more frail people (approximately 50-60 years of age and above), they suggest that 10-15 repetitions may be more appropriate.
Adding a social component to your training is a great way to help you tie it all together and stay accountable for the long haul. Find a buddy, join a class, hire a trainer, join a BodySpace group, or make a list your goals and share it with a loved one. Better yet, do all of the above. Do whatever it takes to fully commit. That is your mantra now: "Whatever it takes."
For every person who lifts weights these days, it seems there are two who have a podcast about it. There are more bodybuilding tips promising greater strength and muscle than ever before, and along with them a ton of confusion; one buffed-up Instagrammer says lifting heavy will get you swole, while a well-known fitness personality has claimed in recent years that two 30-minute workouts per week netted him 34 pounds of muscle in a month.