Speaking from experience, if I am pretty stressed out (which incidentally happens rarely) and I try to have a decent meditation session, it rarely works well for me. For a start I'm not adequately prepared eg, not in the present moment and still in problem solving mode. From my observation of others when they're stressed and try to meditate they become further frustrated because they're unable to stay focussed and get into the zone. The secret is to prepare yourself adequately first rent power generator.
Find yourself a technique you know you'll enjoy so practising will be a positive experience. Alternatively find yourself a meditation group that has a good teacher. Not only will you learn to meditate, you might also form some great friendships that will last a lifetime.
Meditation is a discipline that can be learned through a step by step process, and once adept, you can use it for any number of reasons. Decide if your meditation is for relaxation; connection to spirit or self; to achieve clarity of mind; or to regain some inner strength .
My reasons for meditation are numerous. I meditate on purpose to receive answers to questions I might have. Before going into a meditative state I write down exactly what my question is, give it a timeline, and wait. Generally the answer is received during the session or shortly afterwards, depending of course on the timeline I gave.
I'll also meditate to access my creative self. After I've jotted down what my intention is I go into a meditative state with pen and paper handy. Generally what happens for me is that I start receiving ideas one after the after which I quickly jot down. I've written an entire workshop through one of these meditation sessions.
A great self healing tool, whenever I feel 'flat' I'll use colours, crystals, sound, and essential oils for my meditation sessions. After each session I am lighter, centred, balanced, and more focused .