Not able to do what you used to do?
Most people at some point in their lives have that moment where they realise they can't "do what they used to do" or can't get away with what they used to do. This is a health and fitness blog so I'm referring to that moment you're aware of not being able to train as much/long/hard anymore, or can't do "X" "Y" or "Z" without breaking down with an injury or some kind of niggle.
While age is a poor excuse to stop training or doing things you have always done and enjoyed, I will say if you're 35 or over and not doing things correctly you will start to hit stumbling blocks! In my humble opinion these "stumbling blocks" can be overcome with some simple tweaks which I have outlined below:
1) Understand training is a stress on the body! - Now you're a little older its likely you have more commitments such as a family, big mortgage and a more demanding job or role in your company. The body really just perceives stress whether its from lack of sleep, important deadlines at work, family issues or training down the gym. Be honest with your self if your life is already choc full of other stressors then don't expect to be able to train as hard or as frequently as you did as a 25 year old with much fewer commitments. If you used to train "hard out" 5 days a week for an hour a time, then cut back to 3 times per week for 45 minutes. Don't just quit but be realistic about what you can handle factoring in the overall stressors in your life. Tweak things until you find a regime that suits you and your current lifestyle.
2) Warm up properly! - This should be blatantly obvious but too many people don't prepare themselves correctly to train and pay the consequences for it. While you don't need hours of foam rolling and stretching, 2-3 mins on the cross trainer alone won't suffice unless its simply to get some blood pumping before you do the specific stuff. If you've been sat at your desk all day its likely you need to mobilise areas such as the hips and thoracic spine along with ramping up tension in key muscle groups like the glutes, upper back and abdominal region. This is being fairly generic admittedly so think about what you're training that day and use your common sense. If you intend to train upper body with overhead movements (pull ups and overhead presses etc etc) then make sure your shoulders and scapula (shoulder blades) are mobilised through both the range of motion you have available and also the range of motion of the intended exercises! (If the two of those don't match each other please read tip 3!). I like using CARs (Controlled articular rotations) for specific joint mobility (Google CARs and Functional range conditioning there's plenty of online resources..).
3) Pick exercises that respect your limitations! - If you have poor overhead mobility yet still use exercises such as chin ups and military presses then understand you might eventually get found out and get hurt. The same goes for deadlifts from the floor if you're unable to keep a neutral spine etc, you get the idea. If you can deadlift off blocks or off the pins and maintain good form then this a far safer option for you and way less injurious. The same goes for overhead pressing and pulling, switch to high incline pressing variations that are congruent to the overhead mobility YOU have. Don't do exercises simply because everyone else is doing them or an article in some magazine told you was good to do. I'll often have clients use a lat pull down machine and lean back slightly if they have poor shoulder mobility, OR better still use rowing movements to work the back and lats?? The last thing I will say is every exercise you put in your training program ask yourself this question, "how will this effect me in 5-10 years time?". If you feel you're pushing the envelope then modify and stay safe, play the long game!
If you're unsure then always consult with a good and well qualified personal trainer to assist you and give you the proper guidance on the above. You can always contact me directly on firstname.lastname@example.org, or if not look for personal trainers that have done courses such as RTS (Resistance Training Specialist), FRC (Functional Range Conditioning), FRA (Functional Range Assessment) or things similar. It will be well worth the investment in hiring even if just for 2-3 sessions.