Here are some do's and don'ts I have learned from my own personal experience and observation of the master’s athlete:
Find a routine; be consistent in the time of day and the place you train. If you can find a training partner or a group to train with that will help with routine.
Look at your driver’s license. Yes you are getting older, so train accordingly. Use your age and your experience to your advantage. Trying to be a teenager again will only hurt, not help.
Don't get athletic amnesia. Forget what you did in college or in your 20s, be realistic in your expectations and what you are trying to achieve now, it is futile to try to repeat workout you did in your twenties. Most of the time this will result in injury.
Do things you like. This really depends how competitive you want to be. If you want to be a national class or international class master’s athlete then you still are going to have to some uncomfortable workouts. If you are training to be athletically fit then being uncomfortable is not necessary
Compete against or measure against yourself. This is true at any age. Measure your progress against yourself. I know I have a certain lifting workout I use as a benchmark to gauge my overall strength and ability to handle my bodyweight. The same is true for biking, I have a particular route I test myself on four times a year to gauge progress. For me and I think it is the same for most people it is about goal achievement, not goal setting.
Allow adequate time for recovery. As you age it takes longer to recover from the stress of hard workouts. Build in more rest days.
You must strength train regularly. More frequent strength training is the closest thing there is to the fountain of youth. Leg strength and core strength will have a significant positive impact on posture. For both the male and female master’s athlete the endocrine hormonal benefit is tremendous. A well designed strength training program can stimulate growth hormone and testosterone production which will help maintain lean muscle mass. In addition it can slow the loss of type II muscle fiber.
Stretch daily! We lose elasticity in the muscles and tendons as we age. Some researchers have identified the subsequent loss of flexibility as a factor in degenerative joint disease.
Respect old injuries - they will come back to haunt you. Just like training, injuries are cumulative. The small niggling injuries that you could ignore when you were in your twenties will now cause you to miss days of training and if ignored weeks of training. Learn to read and listen to your body.
Don't listen to the naysayers - you can do what you want to do!