Virtually everyone will tell you to just do Starting Strength or Stronglifts 5x5. Both are fine, both require 3 workouts a week of ~45 minutes each.

If you're willing to monitor your diet a bit and stick to the program, then you'll truly see amazing gains in a year.

I can attest to Stronglifts 5x5, which takes only 45 minutes 3x a week, and can keep you going for 6 months with amazing results. Pure strength weight lifting has the biggest impact on health out of any fitness activity I've ever tried.

One thing to note as with all lifting especially squats, depending on age, DOMS may be severe. The program starts as light as possible but even that may be too much. If starting from a very sedentary lifestyle it's probably best to start with a couple of weeks of cardio and light movement before lifting.