Two pieces of important gym equipment include a workout journal and stopwatch (interval timer). The fitness log lets you consistently measure progress. The stopwatch (or interval timer) lets you measure the third variable at the gym, time. Who did more work the person A that does 5 exercises of 3 s...
i use a stopwatch on walking routes I use a lot. It's very motivating for me to beat a previous "best" time. It also lets me know that I am walking at a good pace, and not just phoning it in. It is also good for runners or joggers. You can find a cheap stopwatch for under $20.