There are a handful of items that I use regularly for myself or with clients that I find are effective in releasing tension and making muscles a lot happier. The first of these items are spikey balls.
As the name says these are firm balls with small little spikes on them. They sound quite harsh but in fact can really help to relieve tension built up in certain muscles. I much prefer using these over a foam roller for several reason.
Firstly they are smaller and fit into a kit bag so you can have them whenever you need them. Secondly they can get deeper into certain muscles such as your gluteals unlike a foam roller. They are great at getting between the shoulder blades and you can use them on trigger points (small areas that are really sore). They are not expensive.
Investing in two balls will really help you at work or when working out. Below is a video that you can add to your stretching and muscle releasing part of your training.
Have a try and see what you think a lot of my hockey players use them to help them get through the season. If you are experiencing muscle pain that will not go away after rest and muscle release then please consult a doctor, physio or sport therapist as you may have an injury or another underlying issue that needs professional help.