When have you felt at your strongest before? What was happening at that time that gave you that feeling. What were you doing physically that helped you feel strong. It may have been regular walking, it may have been yoga, pilates, running, weight training... It may have been a period of your life where you had to find emotional or mental strength. We are all different and I believe strength can be found in many different places and activities (not just 'strength training').
Personally, I find that when I feel strong physically, I feel an overall sense of strength elsewhere. I'm more confident within myself and I feel that I can take on whatever comes my way. Conversely, when I feel strong mentally and emotionally I also feel like superwoman physically. Infact the best strength training I ever did was when I climbed regularly because I completely integrated mind and body. I faced my fears on the climbing wall, strengthening my mind, and my body had all over strength like I've never felt before.
What does strength mean to you?