Don't Push Beyond Your Skill Level
Here are the Multisports OC Safety Suggestions For Training & Racing.

General Safety Suggestions

Take personal responsibility for your safety and well-being.
Don't expect others, including the coaches, to be responsible for your safety and common sense.
Know your personal limits and be prepared to stop in a practice or race that is beyond your skill level to complete safely.
Let the coach and other athletes know if you are at practice where you know of a potentially hazardous situation that they may not be aware of, or if you think the conditions are beyond your personal safety and skill level.
Coaches are not there to think for you, they are there to instruct and encourage you to reach your personal potential and goals.
Some of the tasks they will ask you to perform will involve a degree of risk that you need to either accept or choose not to attempt.

Sport Specific Safety Suggestions

Don't swim alone - especially in open water.
Let the lifeguard at the beach or lake know your training route and plan
Ask about any special circumstances to be aware of such as extreme water temp, currents, waves, dangerous sea life, etc.
Improve your technique, endurance, and open water swimming skills to lower your risk potential.

Try to avoid riding alone.
Always wear a helmet (properly fitted)
Get a RoadID bracelet or shoe attachment with emergency contact info
Never assume a car sees you.
Never ride in the dark without a front and rear light and reflective clothing.
If you must ride in the dark consider a trainer ride or going on a bike trail where there is no car traffic (however lighting on bike trails is often not good).
Look for yourself when crossing traffic lanes. Don't just follow other cyclist in a group without looking.
Improve your bike handling skills so you are better prepared to deal with hazardous conditions such as potholes, obstacles in the road, wet and slippery conditions, sand or gravel, and riding in a group.
Always let someone know your route if you ride alone & carry emergency information and ID
Also review our MSOC Cycling Practice Etiquette Info

Try to avoid running on trails alone
Try to avoid running in the street, especially in the dark.
If you do run in the street, run against traffic, even in the daylight, so you can see the cars coming at you to avoid being hit from behind.
Wear reflective clothing when running in the dark.
Always let someone know your route if you run alone & carry emergency information and ID

Do not attempt, or be prepared to modify, a high intensity or long endurance training session if you are not properly fueled and hydrated, or if do not have adequate replenishments for the conditions.
Additionally, be willing to modify your training plan if you are sleep deprived.

Use common sense and don't push too hard to train or race through an injury or sickness. Recovery is an important part of improvement and longevity in sports.