When writing messages in a retirement card, it's best to focus on the positive aspects of retirement and on the personal relationships shared with the retiree. It's possible that the retiree is going to miss coming to work every day, so messages that bring up a sense of loss or sadness should be avoided. Sharing memories with the retiree and pointing toward something hopeful in the near future are both welcome ways to sign a retirement card.
Many people like to crack jokes about retirement, perhaps because doing so adds a light tone to a moment that is sometimes sad for both the retiree and the co-workers he or she leaves behind. Office inside jokes or expressions of faux jealousy for all the fun and free time the retiree is about to have are always appropriate on a retirement card.
It's also possible for retirement card wishes to be heartfelt and meaningful, especially if the retiree has mentored many co-workers or has deep relationships that extend beyond the workplace. Because many retirees have little idea how they will spend their new free time, penning an invitation to lunch, a round of golf or even a quick cup of coffee can be very encouraging and appreciated as well, as are expressions of admiration and gratitude.