There is a new challenge every day. Every project has its own unique problems which need to be solved. Aside from that the industry is always changing. Lighting for example, LEDs were not commonly used 10 years ago, now however they are all i use. Their technologies are constantly changing offering new solutions. Our world as engineers is constantly evolving and we need to work to keep up with it. It makes it enjoyable and it is certainly not your average mundane “do the same thing every day” job. Plus its a skill/profession/trade which will always be in demand. As long as you apply yourself you will always find work.
That I could use the algebra I learnt at school. I never though I would! I also get a lot of pride. I feel engineering is a very respectable career and I know I am making a difference to the future of our technology and the way we live.