Building from the ground up...

Wuffles70

So, (a very) long story short... I've never been a massively sporty person. Over the years I've done lacrosse, trampolining, swimming and running but I've never excelled and my stamina has never been great. This, combined with some health problems which have turned out to be mostly due to anxiety, has left me feeling very low on energy and flabby. Aside from a pretty benign congenital heart defect, I am fine - just unfit.

I want to start building a routine that cuts down my body fat as fast as is healthy, gives me plenty of energy and, when I'm able to, involves lifting heavy weights for strength. At the moment, I'm walking about 3 miles at a brisk pace every other day and doing 40-60 minutes of yoga 6 days a week. I'm also doing the occasional bit of muscle work outs but it's very light - I can just about crack out 10 push ups. Where do I go from there? Building up stamina by doing a couch to 5K feels like a sensible step but what comes after that? How do I even begin with strength? Is yoga enough for my flexibility?

Please help me, athletic people! I'm feeling OK about figuring out what I should be eating but this part is leaving me stumped...