You can't just focus on one... You have to open all of them... If that's not the problem... Sorry beyond that my knowledge in the subject is limited...
Aside from holding poses and meditating into states of higher vibrational function, you also have to be proactive in maintaining your chakras: opening them, keeping them clear of gunk, keeping them in alignment and balanced with one another, making sure they serve as a continuous flow conduit as opposed to a series of dams that may/may not allow access at any given point... There are lots of great chakra resources out there, from basic The Idiot's Guide to dissertations and personal reflections and meditations from well versed and experienced gurus. While chakra yoga is a great tool, it's not everyone's cup of tea. Aside from the meditating and the getting into various pretzel poses, also make sure you evaluate the parts of your life/personality that are goverened under each individual chakra. From personal experience, whenever my Anahata energies have been out of whack, it's because I'm being selfish, cowardly, or am fixated with too much hatred/rage/negativity towards either myself or towards others. If you struggle with self confidence and self assurance, do things to work on that to alleviate the blockages of that particular chakra. If you're having issues with other people, or maybe have been kind of a turd lately towards humanity in general, spend some time reflecting and centering and get in a good head (and heart!) space. Also, it doesn't hurt to get out there and do some selflessly charitable work and good deeds for others :)
I'd suggest working on some shielding, if you want to work on your heart chakra and there are loads of negatives vibes flying around. That way, you can begin to regain the positivity of having your chakras healthy, but not so that it would make you vulnerable. Try exercises in cleansing and flexibility, so that you can enjoy your safe time, and create a haven from the bad environments you're having to face. It may help you to wear a rose quartz necklace, and hold it while you're meditating.
Also, make a point of doing things that you love to do. Perhaps you are creative? Or you like to walk. Whatever you love doing, do it lots! I wish you good healing :)
Hm, well in my bos I have some stuff, I'm not sure wheather it's to open them or maintain them but yeah;
Exercises - Push ups & Swimming.
Foods - Green vegetables, green tea.
Herbs - Basil, Sage, Thyme, Parsely.
Stones - Malachite, Emerald, Rose Quartz.
I'm not sure but these are associated with the heart chakra, maybe keeping a rose quartz in your pocket would help. I would suggest trying to open all of chakras though.
